proceedings of the academy op

128 PROCEEDINGS OF THE ACADEMY OP

laterali,

tumidula

; striisregularibus distantibus^; epidermideflavescentein- duta; valvis solidiusculis, intus _albis,

umbonibus

prominentibus, erosis, cardinecrasso, tridentato.

Long.^11;lat. 10;diam. 6mill.

Hab.

'(Collect. Prime.)

14. Corbicula vio1acea Prime. C.testa ovato-transversa, subaequilate-

rali, obliqua, extremitatibus _{aequaliter obtusa,} transversim irregulariter striata;epidermidesqualide virescente vestita^;

umbonibus

_{magnis, obliquis,}

erosis,intusprofunde^violacea;cardine angustotridentato.

Long. ^{15; lat.}13; diam.8mill.

Hab.

^? (Collect.

Jay

^etPrime.) 15. Corbicula

Agrensis

^Prime.

CyrenaAgrensis Kurr., in ^litt.

C. testa ovato-transversa, aequilaterali, laevigata, depressiuscula,extremi- tatibusrotundata;epidermideviridi-olivaceainduta; sulcis regularibus, ^dis- tantibus;intus pallide violacea^;

umbonibus

tumidis, erosis^;cardineangusto, dentibuscardinalibuscrassis, lateralibus aequalibus, tenuiter serrulatis.

Long. ^{9;lat. 8;} diam.5mill.

Hub.

Agra, India. (Collect. Prime.)

16. Corbicula

inaequilateralis

^{Prime. C. testa ovato}transversa, depressiuscula, tenui, inaequilaterali^; extremitatibus rotundata;

umbonibus

prominentibus, approximatis, ^antice obliquatis, violaceo subradiatis; sulcis regularibus,intus pallide violacea^;epidermidepallide virescenteinduta;car- dine angusto^;dentibuscardinalibuscrassis, lateralibus inaequalibus.

Long.^16;lat. 12;diam.8 mill.

Hab.

Africa. _(Collect. Prime.)

17.

Sphaerium Vermontana

^{Prime. S.} testa ovato-trigona, tumida, inaequilaterali,, ^striisregularibus, epidermideviridi-fiavescente vestita;

um-

bonibus tumidis^;cardine arcuato; dentibuslateralibus crassis. _,

Long. ^11;lat.10; diam. 7mill.

Hab. Vermont,

N. America. (Collect. Prime.)

This_species,

though somewhat

^{allied to}Sph.

striatinum

_Lam.,is

much more

inequilateral.

Descriptions ^of

new

PalaeozoicFossils from Illinois

and

Iowa.

BY

^F. B.

MEEK AND

A. H.

WORTHEN,

OftheIllinoisStateGeologicalSurvey.

ECHINODERMATA.

CRINOIDEA.

Genus PLATYCRINUS,

Miller, 1821.

Platycrinus Oweni.

Body

^rather large, cup-shaped, ^or sub-hemispherical

below

the

summit

ofthefirstradials,

rounded on

the

under

_side,height about two-thirds thebreadth. Base saucer-shaped, ^ornearly^fourtimes as

wide

as high, pentagonalⁱⁿoutline, the sidesbeing nearlystraight or slightlyconcave, sutures anchylosed;

columnar

facet large,^itsbreadth_equallingabouthalfthat ofthebase, concave,

margined by

^aslightly raised

somewhat

undulated _rim,

and

_perforated

by

^a large central opening. ^{First radial} plateslarge, sub- quadrangularⁱⁿgeneraloutline, but havingthe superior ^lateral angles ^trun- cated for the reception of the anal

and

interradial_pieces, widening^alittle fromthebase

upwards

^{; facetfor}the reception of the second radial pieces

[June,

NATURAL SCIENCES OF PHILADELPHIA. ]29

prominent, nearone-third aswideasthe_plate,

and

_extending

down between

one-third

and

one-halfitslength. Secondradial pieces small, extending out nearlyhorizontallyfromthefirst;

round

_below,

and

_presentinga pentagonal outline, as seenfrom the

under

side, supporting

on

their superior (outer) slopingsides, the

two

firstdivisions ofthearms. Firstanal piece rather large fora_{species of}thisgenus,apparently pentagonal,

and

_extending

down between

thefirstradials,nearly^asdeep^asthe articulating^facetssupporting^thesecond radial pieces. (Otherparts

unknown.)

The

suturesseparating^thefirstradial platesfrom each_other,

and

from the base, are rather distinctly canaliculated, inconsequence^ofthe beveling^ofthe edges^{of the}plates.

The

surfaceisfinelygranulose,

and ornamented by

^small obscurely subnodosecostae,of

which

there are

two on

thebase passing

around

nearthemargin. Threesimilarcostae

ornament

thefirst radial plates,being arranged parallel to the basal

and

lateral margins, but

becoming

nearly^or quite obsoleteabovethemiddle.

Named

in

honor

ofProf. Richard

Owen,

ofthe Geological

Survey

^ofIndiana.

Localityand_position. Burlington, Iowa. Burlington Limestone. Collec- tion ofMr. Charles

Wachsmuth.

Platycrinusscobina.

Body

rather small,cup-shaped^orsubturbinatebelow the

summit

ofthefirstradial pieces. Base basin-shaped, about ^{twice as}wide as high,

and

rather

more

thanequalling one-third the height^of the

body

^to the _top of the first radials; pentahedral in outline, with _slightly concave sides,

columnar

facet lessthanone-thirdthebreadthofthe base. First radial plates slightlybroader than _high, widening ^{a little}

upwards

^fromthe base, presenting^asubangular^outline, the superior ^lateral angles being truncated forthe reception ofthe anal

and

interradial pieces^{; facet for} the reception of thesecondradial piecenot protuberant, concave,^ratherlessthanone-thirdthe breadthofthe

upper

side of thefirstradial plates,

and

_extending

down

about one-fifththeir length. Secondradial pieces small, triangular,

and

_supporting

on

their superior sloping sidesthefirstdivisions ofthearms. After dividing

on

thesecondradial pieces, the

arms

divide again

on

thesecond_pieceabove,

beyond which

they^arelong,slender,

and

_{apparentlysimple.} After thesecond bifurcation, they^areeachatfirst

composed

^ofa single^series of

wedge-shaped

pieces,but gradually pass ^intoa doublealternating series of pieces, eachof

which

isaboutaslong^{as wide.}

The

surface ofthe basal

and

firstradial plates^is

ornamented

with

numerous

small, rathersharplyelevated, irregularlyarrangednodes, or coarse granules, so as topresenta rasp-likeappearance.

The

suturesare closelyanchylosedⁱⁿ the base,

and

well defined

between

thefirstradial_plates.

Initssurface

markings

^thisspecies^is

much

like P. Wortheni_{of Hall,}but it differsinhavinga distinctlyprotuberant, instead of a flat or concave _base,

and

inhaving but^four

arms

toeachray, instead ofeight or nine.

Locality

and

_position. Burlington, Iowa. Burlington Limestone. Mr.

Charles

Wachsmuth's

collection.

Platyckinus (Pledeocrinus) asper.

Body

small, rather deeply ^basin-

shaped

^{belowthearms.} Base

much

depressed, largely

and

deeply excavated below, with a

narrow prominent

marginal rim,

which

is notched at the sutures,

and somewhat

undulated. First radial plates broaderthan_high, widening moderately

upwards and

_presenting a subquadrangular outline, but _really hexagonal, ⁱⁿ consequence ^of the truncation of the superior lateral angles ^for the reception of the interradial

and

anal plates^; sinus in the

summit

_{of each,} for the _reception of the second radials, deep, semi- circular,

and

_equalling about half the breadth of the

upper

^{side; surface} ofeach

ornamented by

^a very prominent, sharply ^elevated carina,

which

passesacrossnear the lower_side,

and

is

waved

or oftenbroken

up

^intoisola- ted prominences. Second radial pieces triangular, wider than _long,

and

1861.]

130 PROCEEDINGS OF THE ACADEMY OF

nearly entirely received within the _{sinus, in} the

upper margin

^{ofthe first} radial pieces. Firstanal

and

first interradial plates of apparently ahout the

same

size, theformer connecting with ^a range ^of small_{plates above,}

which

form the

under margin

^ofthe lateral analopening.

The

_arms, afterthefirstdivision

on

the second radial plates, divideagain on the second _piece, above

which

the

two

inner branchesbifurcateagain

on

thesecond piece, thus

making

^six

arms

in each ray seen in the

specimen under

description.

Above

thelastdivisionthe

arms

are slender, very gradu- allytapering,

and

each

composed

^{ofadouble seriesofsmall}alternating pieces, (excepting near the points of bifurcation,)

and

_support

on

theirinner side ratherclosely setrangesof tentacles.

The column

isalittlecompressed,

and composed

of rather thin pieces,with

prominent

crenulated margins near the base.

Locality

and

_position. Burlington, Iowa. Burlington Limestone. ^Collec- tion ofCharles

Wachsmuth.

Genus FORBESIOCRINUS, Koninck and Le Hon.

Fokbesiockinds Moxeoensis.

Body

^{below the free}

arms

_apparentlyskort- turbinate, or subglobose,

composed

^of nearly smooth, rather thick _plates, connected

by

linear sutures. Base _small,

and

nearly hidden

by

^thecolumn.

Subradial_{plates of}moderate_size, four of

them

pentagonal,

and

one

on

the anal side apparently hexagonal, with

unequal

^{sides. First radials about} twice as wide as high, hexagonal ⁱⁿ form,

and

_nearlytwice as large asthe subradials. Second, ^third

and

fourth _radials, in

two

ofthe _rays, (and the fifth

and

sixth in another,)^all nearly^ofthe

same

_{length,hexagonal} inform

and

abouttwice aswide as long. Last

primary

radial pieces ofnearly the

same

size as the _others,

and

_supporting

on

their superior sloping sides the secondary^radials.

Of

the

numerous

interradials,the first is about thesizeof the subradial pieces, hexagonal ⁱⁿ form,

and

_supports

two

smaller _pieces inthesecond range.

Above

these four or five occurinthenext_{range, in}oneinterradial space,

which

isasfar

up

^asthey can be counted ⁱⁿ the

specimen examined, though

^{it isevident}from the breadthofthe interradial spaces, thatthey

must

increaseatthe

same

rateforseveralranges above. (Analplates

unknown.)

The column

is

rounded and

comparatively thick ^{at its} junction with the base, from

which

ittapersgradually towards^the lower extremity.

Near

the baseitis

composed

^ofextremelythin, equalsegments, connected

by

minutely crenulatedsutures. Farther

down

itgradually passes^into a series of alter- nately^thicker

and

thinner_pieces.

After the first division of the rays

on

thelast

primary

radial pieces, the

arms

divide several times,

and

_appear to give off lateral branches, but our specimen^isnotina condition toenableustodetermine

how many

pieces ^in- tervene

between

the points of division, nordo they

show whether

ornotthere are

any

interaxillary pieces.

The

_specimenbeforeuspresents the peculiar

and anomalous

_appearanceof

having

^asmallfalse

arm

arising directlyfrom the

summit

of the

upper

^trun- catedsideofthelargest subradial piece. ^It

seems

eventobe inserted into a sinusinthe

upper

^sideofthe subradial, yet

we can

scarcely believe^itisany- thing but one^ofthe smallerdivisions of thearms,accidentally

broken

off

and

placedⁱⁿthat position.

As

nearas

we

can determine from a description alone, this species appears tobe

somewhat

closely related^to F._exculptus, (Onychocrinusexsculptus,

Lyon

and

_Cassiday,

Am.

Jour. Sci.vol.29,N. S.page 78,)butdiffersinhaving^less

produced

basal pieces, while the

upper

angles ^of the subradials are obtuse instead of "quite sharp." ^Italso

seems

to

have two

or three

more primary

radial pieces inone ray than occurⁱⁿ

any

^{ofthose ofthe}species described

by

Lyon and

Cassiday.

Again

^itssurfaceappears ^tobe

smooth

instead ofgranu-

[Juue,

NATURAL SCIENCES OF PHILADELPHIA. 13l

lose,

and we have

notbeenable to see

any

indications of the small _patelloid pieces between theradial

and arm

_{pieces as}in F. exscu'ptus.

Locality

and

_position. River _Bluff, near the south lineof

Monroe

_County,

Illinois.

Keokuk

Limestoneofthe

Lower

Carboniferousseries.

ForbesiocrinusAgassizi, var. giganteus. Thislarge Crinoid^differsfrom the typicalspecimen^ofF. Agassizi (Hall), in

having

^four instead of three plates ineach secondary ray^; (in three of therays seen)whilethere are

some

differ- ences inthe

number and

arrangement^oftheanal

and

interradial plates. ^It alsodiffersinhaving^its

column

almostexactly cylindrical^foradistance of at least four inches below the _base, while that of F. Agassizi,^isdescribedas

"rapidlytaperingbelowthe

summit." We

suspect^it

may

prove^tobeadis- tinctspeciesfromthat described

by

^Prof.Hall, but as it agreeswithhisdes- cription

and diagram

ⁱⁿ

most

ofitscharacters, excepting the points of^differ- ence

we have

_mentioned,

we

_merelycall attention to it as a variety^ofthat species, until

we

can

have

an opportunity^to

compare

^better

examples

^{of it} with authentic specimensor figures of^Prof. Hall's species. Should it prove tobe_distinct, itcan takethe

name

_giganteus,

which would

_{be veryappropri-}

ate, sinceitisthe_largestspecies of thatgenus

known,

the length ^{of its}

body

tothe

commencement

ofitsfree

arms

_{being near}3-30inches,

and

itsbreadth apparently about the same. ^Its

arms

are proportionally short,

and

bifurcate frequently.

Localityand_position. Burlington, Iowa. Burlington Limestone.

Genus ACTINOCRINUS,

Miller, 1821.

Actinocrinusdodecadactylus.

Body

rather small, subglobose^;

summit and

calyx below the

arms

of nearly the

same

size; breadthalittlegreaterthan

the-height^;

composed

of slightly convex,

smooth

or subgranulose ^plates,

which

areconnected

by

moderately^{distinctsutures.} Base _small,

much

de- pressedor subdiscoidal, obtuselyhexagonalin outline,withthree otherobtuse retreatingangles^atthesutures. First radial plates wider thanlong, three of

them

_{regularlyhexagonal,}

and two

heptagonal. Secondradial pieces

much

smaller than the _first, about twice as wide _{as long,}

and

allquadrangular.

Third radialsalittlelargerthan thesecond, ^all regularlyhexagonal, the

two

lateral margins being very short,

and

the

two

superior sides each about equalling the ^{base. In the}

two

posterior rays, the third radial pieces each support on one of their superior sloping sides a large brachial piece,

and on

the otherasecondary^{radial of}near the

same

_size,which,initsturn, supports

two

brachial pieces,

making

^three

arms

toeach oftheserays^;whileinallthe others,

two

brachial pieces ^rest directly

upon

^{the third}radial, thus

making

only twelve

arms

inthewholeseries.

The

firstanal plate^isaboutaswideas thefirstradials,buta littlelonger, being longer than wide, instead ofthe re- verse. It isregularlyheptagonal,

and

_supports

on

each_superiorlateralslop- ingside,asmaller heptagonalpiece^; while

an

elongated, coffin-shaped piece rests

upon

^its short superiortruncated_side,

between

the

two

_latter,

and

ex- tends up, flankedoneither side

by

^thefirstbrachials, to^its connection with the

summit. Each

oftheinterradial spaces^isfilled

by

a single ovate, octago- nal_piece, aboutas large asthe second

and

third radial pieces taken_together.

The

vaultis

composed

^ofrather large,

somewhat

_{regularlyarrangedplates}

which

are very nearly flat, the smaller onesallbeing on^theanalside; the proboscis^issmall,

and

locatednearertheanalthanthe dorsalside.

Height^tobaseof proboscis, 0-50inch; breadth, ^-58inch; breadthof base, 0-23 inch.

Locality

and

_position. Burlington, Iowa. Burlington Limestone.

Actinocrinusptriformis, var. rudis. Actinocrinus pyriformis,

Shumard,

1855, Geol. Reportof Missouri,p. 192, pi.A, fig. 6,a, b.

Body

exclusive ofthe proboscis piriform,being very

narrow and

_apparently

1861.]

132 PROCEEDINGS OF THE ACADEMY OF

cylindrical from the base to the top of the third radial plates,above

which

the secondary^radial

and

brachial piecescurve abruptly outwards^tothe base of thearms, ^{so asto}form withthe ventricose

summit

a

much _expanded

vis- ceral cavity, entirelyabovethe basal

and primary

^radial plates. Baseun-

known

; firstradials

unknown,

excepting from

some

_{remaining portions} of their

upper

ends,

which show

that they^are comparativelylarge. Second radialsverysmall, a^littlewider thanlong, (those seen)irregularlypentagonal in form, oneofthe sidesbeing

much

shorterthan the others. Thirdradials aslong^asthefirst,

and

_nearlyone-third wider, (the only

two

visible inour specimen,)hexagonal ⁱⁿ form,

and

each supporting

on

its superior sloping sides

two

_secondaryradialsofaboutits

own

size.

Each

oftheseis

surmounted by

^a

^somewhat

largersecond secondaryradial,

which

initsturn supports

two

firstbrachial pieces, eachof

which

issucceeded

by

^a second, from

which

the free

arms

aregiven^off.

The two

series of secondary radials,

and

the

fmr

series of brachial pieces in each ray, connect _laterally, so as to leave

no room

forinteraxillary

and

interbrachial pieces. Interradial plates

two

or three, the^firstbeing about^the

same

sizeasthesecondradials,

and

_hexagonal orheptagonal^inform.

Above

thisthere areoneor

two

smallpieces, of variable size

and

_form,over

which

the secondaryradials,

and

thelateral seriesofbra- chial pieces of the rays

on

each_side, connectallthe

way up

^tothefreearms, insuch a

manner

astoleave

no

_spacesforinterradialsabovethose just descri- bed. (Analplates

unknown.)

Dome

hemispherical,

composed

^ofpentagonal, hexagonal,

and

_heptagonal plates ofnearly uniform size, each of

which

is provided witha spine-like tubercle. Proboscis central or nearly ^so.

Arm

openings twenty. ^Surface

smooth

orobscurely granulose^; smallratherpointedtubercles are also seen

on

the second

and

third radial _plates, first interradials,

and

firstsecondary radials.

It ispossible thisCrinoid

may

^bespecificallydistinctfrom A.pyriformis, of

Shumard,

^butitagreeswithitinso

many

respects that

we

do not feel fully warrantedinregarding ^itas specifically distinct. Its

most

_important differ- encesare the sub-spiniferous character of^itsplates,

and

the possession ofonly

two

or three interradial _plates, instead of six in eachinterradial space. ^It alsodiffersinhaving^a

more

ventricose

dome,

^{while the inferior half of its}

body

^is

more

_abruptlycontractedbelow the arms.

Locality

and

_position. SaltLick_Point,

Monroe

_County,Illinois.

Where

it

occursinbedsofthe

same

_age asthe

Chouteau

LimestoneofProf. Swallow.

Actinocrinus

(Amphokacrinus

?)cofCAvcs.

Body

small, subglobose,broader than_{high, a}littleoblique^;

summit

_nearlyflat;

under

side

rounded and

dis- tinctlyconcave, sides rising vertically ornearly^{so. Surface}

smooth

or sub- granulose. Base_small, concave,

and

_entirelyincluded within the concavity ofthe

under

side. First radial platescomparativelylarge, convex,

and

curv- ing under, ^{so as to} form _{a part of}the concavity below;

two

of

them

hept- agonal,

and

threehexagonal. Secondradial pieces(wantingⁱⁿ

two

ofthe rays ofthe specimenbefore us,)widerthan_long,

and

quadrangularⁱⁿform inthe others.

Third radial pieces smaller than the second, (in three of therays,) pent- agonalin form,

and

each supporting

upon

^its superiorsloping sides the first

brachial_pieces,

which

forma part ofthewalls of thebody. First interradial pieces, comparativelylarge, oraboutone-half thesizeofthefirstradial plates, nine-sided, the superior sloping sides ofeach supporting one side of

two

of thebrachial pieces, while

two

_{very smallpieces}rest

upon

^the middle ofthe

summit, and

connect withthevault above,

and

with the brachial pieces

on

eachside. Firstanal_{piece a}littlelargerthanthefirstradials, heptagonalⁱⁿ form,

and

_supportinginthenext range^threepieces, the

two

lateral of

which

are larger than the _other,

and

connect above

on

their slopingsides, with brachial pieces,whilethemiddle_piece

between

theseisirregularlyhexagonal,

[June,

NATURAL SCIENCES OF PHILADELPHIA. 133

and

_supports threevery smallpieces in the next _range,

which

connectwith theanalopening,

and

thevault pieces above,

and

withthe brachials

on

each side.

The

vaultis

made _up

of afew comparativelylarge pieces,the central oneof

which

isalittle

more convex

than the others.

The

anal opening ^is verysmall, lateral,orabout

on

the

same

horizon as the

arm

_openings,

and

surrounded

by

only^fiveplates,

which

arenot protuberant. Thereare twelve small

arm

openings arranged

around

the

margin

^ofthe

summit,

^{three to}each ofthe posterior rays,

and two

toeachoftheothers.

The arms would

_appear, fromthesmallsizeoftheopenings,

and

the very small articulating surfaces for thereception of the^{first free}

arm

_{pieces, to be very}slender

and

_fragile.

(Column unknown.)

Height^ofbody, C'31 inch., breadthfrom the anal totheanterior_side, 0*42 inch; breadthof base, 0*17 inch.

This is a very remarkable species,differing from

any

^otherActinocrinus

known

to_us, in theconcavity^ofthe

under

_side,

and

the incurved character ofits firstanal,

and

first radial pieces. ^Its

under

sidepresents

much

_{the ap-} pearanceof Zeacrinus,

though

^{in the}

number and arrangement

^of the parts

composing

^the

whole body

^itwillbe seento possess^allthe essential characters ofthe _greatgenusActinocrinus as it is

now

understood.

We

_place itprovi- sionally inthe sub-genus Amphoracrinus,

on

accountofthelateralposition of the anal _opening, but

we

_suspect it should be

made

the type ^ofa distinct sub-genus. ^{It differs} from Agaricocrinus, in

having

comparatively

much

larger ^firstradial pieces, as well as inthe general formofitsbody,

and

its

much

smaller arms,

which

are also located

around

the

summit,

^{instead of}

around

thelowerpart of thebody.

We

are

under

obligations to Mr. Charles

Wachsmuth,

^ofBurlington, Iowa, fortheuseoftheonlyspecimen

we have

seen.

Locality

and

_position. Burlington, Iowa. Burlington Limestone, ^of the

Lower

Carboniferousseries.

Actinocrinus (Pradocrinus?)amplus.

Body

large, unshaped,

composed

^of

thin,smooth,^orfinelygranuloseplates. Base comparativelysmall,

somewhat

spreading^;

columnar

facet large, or

between

one-half

and

two-thirds as

wide

asthe base,having^asmall marginal^rim.

Column

_{strong, round,}

and com-

posed ^ofthin segments near the body,

where

it has a very

minute round

central cavity. Firstradial plates ratherlarge, alittlelongerthan_wide,

and

allapparently hexagonal, ^therebeing

no

distinctangle^atthe middleofthose alternatingwiththe basal pieces. Second radial plates about two-thirds as large as thefirst,nearlyor quite aswideas long,

and

all hexagonal. Third radialsalittlesmallerthan the _second, hexagonal

and

_heptagonal in form,

and

supporting ontheir superior sloping sides the

two

first brachial pieces,

which

are comparatively large,

and

each succeeded

by

three or four

much

smallershort brachials, beforethe

arms

_passintodoublealternatingranges^of small_pieces.

The

firstanal plate^isas large as the first radials,pentagonal in form,

and

_supports

two

subhexagonalpieces inthenext_range,above

which

there are

some

twelveorthirteenother smaller_{pieces of}variousforms.

The

firstinterradial plates are a^littlelargerthanthesecond_{radials,irregulary}hex- agonal,

and

each

surmounted by two

^rathersmallpieces inthesecond_range,

and

three in the next,over

which

there are six orseven still smaller _pieces,

making

^{elevenortwelveineach}interradial space.

After the division of the _rays on the third

primary

pieces,thebrachials abovethefirstpaircurve nearly horizontally outwards, but are included so as toform a_{part of}thewalls ofthebody.

Beyond

^{thefourth orfifth}brachial, the

arms

consist of a double

row

of smallalternatingpieces, of

which

there are eight or ten ranges,^toa point

where

thefirstbifurcation ofthe free

arms

takes_place.

Beyond

^thisdivision, the

arms

continue to be _strong, rounded,

and

each

composed

^{ofa double series}of short alternating pieces,

though

^the

specimen

1861.]

134 PROCEEDINGS OF THE ACADEMY OP

under

examinationisnotina condition to

show whether

ornottherewere

any

otherhifurcations.

They

^allextend out nearlyhorizontally^atfirst,

and

_gradu- allycurve upwards. Resting

upon

^the inner sloping sides of each _pair of firstbrachial pieces, there^isa rather large interaxillary piece, with three or four

much

smaller_piecesabove.

The

vault is moderately convex,

and composed

^of

innumerable minute

pieces,

and

isprovided witha central, or sub-central proboscis. ^It appears to

have

continued out over the anusasfarastothe third or fourth ranges ^of smallalternating

arm

pieces.

This _{species evidently} belongs ^to the

same

_group as that

on which

M.

de

Vernuil proposed^toestablish thegenusPradocrinus,

which

Prof.

Koninck

thinks does notdifferfrom Ctenocrinus ofBronn.

Locality

and

_position. Burlington, Iowa. Burlington Limestone. Collec- tion ofMr. Charles

Wachsmuth.

Actinocrinus Sillimani.

Body

^{of moderate} size, distinctly stelliform, or pentalobate, asseen from belowor above, inconsequence^ofthe deeply^sinu- ouscharacter of the interradial

and

anal spaces; rapidly spreading from the basetothe third_radials, which, with^thesecondary

and

_{tertiaryradials,}

and

brachial pieces, extend out horizontally.

Summit

_nearlyflat

and

_provided witha rathersmallsub-central proboscis. Basalpieces short, thickened

and

projecting

down

over the

summit

of the column, ^{so as to}forma distinctly trilobate rim, deeply indented ^at the _sutures;

columnar

facetconcave,

and

ratherlessthanone-thirdthebreadthof the base. First radial plates about as large as theanal_pieces,very^thick

and

_prominent; wider thanhigh, three of

them

heptagonal, (theangle ^{at the} middle of the

under

side beingvery obtuse,)

and two

_hexagonal.

Second

radial pieces smaller than the _first, thick

and

prominent, wider thanhigh,

and

_hexagonalinform. Thirdradials about thesizeofthe second, wider than _long, heptagonal ^or hexagonal,

and

supporting

on

eachsuperior sloping side asecondary^radial.

Each

ofthelat- tersupports

on

itsoutersideaseriesofbrachial pieces,

and on

its innerside tertiaryradials,onthesecondof

which

anotherbifurcationtakes_place,

making

six

arms

toeachray, or thirty in the entire ^series.

The

two. secondary,

and

thefour tertiaryradials,aswell as

two

orthree of the brachial pieceson each side ofthem, ^arecoveredinabove

by

^vault pieces.

The

first anal _plate is

hexagonal,

and

_nearlyas large as the first radial pieces. In thenext range above, ^itsupports

two

smaller hexagonalpieces,

which

in their turn support three pieces in thenext_range,the middle one of

which

is larger

and

_longer than theothers.

On

eachside ofthislargermiddlepiece, there are

two

other smallerpieces resting

upon

^the

two

lateralpieces ofthethird range,

and

con- necting with^{the vault}above,

and

withthe brachial pieceson eachside.

The

firstanal_plateisregularlyhexagonal,

and

_supports

two

smaller_{pieces in}the second_range, over

which

there are three or fourstill smaller _pieces connect- ingwiththe vaultabove.

A marked

feature of this species ^is the prominence,

and

_veryprofound sculpturing^ofitsplates. Itsfirstradial

and

firstanal_piecesriseintoelevated transverse nodes,

which occupy

nearlytheir entire surface,

and

_project

beyond

the _base, so as to present a distinct six-lobed outline, asseenfrom below.

From

the

under

side ofeachoftheseprominences, one^or

two

short ribscon- nect with thebase,whilesimilarribsconnect

them

with each other

on

each side.

A

single, rather

prominent

^ribalso passesfrom eachtoa smaller

node on

each secondradial pieceabove.

The two

second anal pieces,

and

allthefirstinterradialsareprovidedⁱⁿthe middle witharounded, rather small, very

prominent

subspiniferous node.

The

third radial pieces

have

a centralprominence, connecting

by

short carinae with the

node

onthesecondradialbelow,^{aswell as}with eachofthesecond- ary^radials above.

On

the latter pieces, these carinae bifurcate,

and

extend along thetertiary radial

and

lateralbrachial pieces,leaving deep depressions

[June,

NATURAL SCIENCES OF PHILADELPHIA. 135

between.

The upper

^anal

and

interradial plates areconvex, but do not gene- rallyriseinto distinctnodes.

Named

inhonorof the venerable Prof. B. Silliman, Sr., of

New Haven,

Connecticut,

who

perhaps did

more

to createaninterest inscientificstudies

and

pursuits, atan_earlyperiod in the history of thiscountry, than

any

^other person

now

_living.

Locality

and

_position. ClearCreek,

Warren

_County, Illinois. Burlington Limestone.

Genus AGARICOCRINUS,

^Troost.

Agaricocrinusgracilis.

Body

^small, truncato-subglobose exclusive ofthe

arms

;

under

sideconcave, ^theconcavity extending out^tothe middle of the secondradial,^firstinterradial,

and

second range^of anal _pieces, all of

which

are geniculated, orabruptly bentupwards,

and

swollen, so as^to formacircle ofhemispherical nodes

around

themargins^oftheconcave

under

side.

Anal and

interradial pieces rising vertically

from

the margins^{of the con-} cavitybelow.

Dome

rather depressed,

and

provided with a short, strong, sub-central spine.

Anal

_{opening small,}not protuberant,

and

placed about

on

a levelwiththe

arm

_openings,

which

are located slightlyabove the middleof the entirebody, including the

dome.

Base_small, concave, nearly ^or quite hidden

by

the column. First radial platesflat,includedwithin the concavityofthe

under

_side,about as wide as long,

and

_apparentlyallhexagonal. Second ^radials slightly largerthan the

first,

and

quadrangular^inform. Third radial pieces shorter

and

widerthan the_second,

and

each provided with

an

obtuse mesial _ridge,

which

connects withthe

prominence

^{ofthesecondradialsbelow;} sub-heptagonal ⁱⁿ outline, the_superioranglebeing^rathersalient,

and

_{the slopes}

on

eachsidesupporting the first brachial pieces. First interradial pieces larger than the first or second radial _plates, wider above the geniculation than below; irregu- larly octagonal ⁱⁿ form,

and

_supporting

two

smaller elongated pieces in thenext range above. ^Firstanalplate small,

and

included within the con- cavity of the

under

side; supportingⁱⁿ the next rangethree largerpieces, the middle oneof

which

issmallerthan the othertwo.

Above

these fivesmaller pieces areseenin thenext_range,

which

is as far asthey can be counted ⁱⁿ the specimen examined. After the first division on thethird radial pieces, the

arms

are each at first

composed

^of a single nodosebrachial piece, but almost immediately pass^intoadoubleseriesofshort alternating pieces,

which

supporta closely^setrange^oftentacles

on

eachside within.

As

_they

do

not bifurcate again, there arebut

two arms

toeachray, or tenⁱⁿtheentireseries.

Near

thebasethe

column

israther slender,round,

and composed

of alternately thicker

and

thinner_plates, withavery small

round

central perforation.

The

surfaceisfinely

and

_{regularlygranulose}

where

well preserved, but _generally appears^tobe smooth.

Locality

and

_position. Burlington, Iowa. Burlington Limestone. Collec- tion ofMr. Charles

Wachsmuth.

Platycrinus Mui/n-BRAcniATus.

Body

^{below the}

summit

of thefirstradial pieces depressed,basin-shaped. Basediscoid,pentagonal ⁱⁿ outline,

moder-

atelyconcave _below,

and

not prominent

enough

^{to be seen in a side view;}

columnar

facetaboutone-third as wideasthe base. First radial plateslarge, broader than_high,

and

_wideningrather rapidly

upwards

^{fromthebase; facet}

forthe reception ofthe secondradial piecesprominent, extending

down

_appa-

rently below the middle of the _plate. Second radial pieces small, trian- gular,widerthan_long,

and

_{extendingobliquely} outwards

and upwards

^from the firstradials.

After dividingon the second_radials, the

arms

bifurcateagain

on

thesecond piece,

and

the

two

inner_divisions,

which

are largerthan theothers, bifurcate again on^thesecond_piece,above

which two

ofthe sub-divisions in

some

ofthe

1861.]

136 PROCEEDINGS OF THE ACADEMY OF

rays again ^divide once more,

making

seven rays ^to

some

ofthe

arms and

eight^to others.

The arms

are rounded, very graduallytapering,

and

each

composed

^{of adoubleseries} of alternatingpieces, supporting^{tentacleswithin.}

The

suturesseparating the^firstradials, as well as those

between them and

the base, are rather distinctlygrooved, ^{as well as} those

between

the succeeding pieces,

up

^tothelast bifurcation ofthefreearms.

The

surface ofthefirstradial plates^isratherconcave,

and between

the_pro- jecting

margin

^{ofthe sinus above,}

and

the marginal grooves^{; the} concave space being

sometimes marked

_{by very}^fainttraces ofsmall_radiatingcorruga- tions.

Very

^smalllongitudinalobscurestriaeor wrinkles,canalsobe seen

by

theaid ofamagnifier

on

theouterside ofthe arms, above^{thelastdivisions.}

This_speciesisalliedtoP. corrugatus of

Owen and Shumard,

^{butdiffersinthe} style of^itssurfacemarkings, being ^{in fact} nearly entirely smooth. It also differsinhaving^{a distinct}marginal groove along^{the sides}

and

baseofits first radial_plates. Its

body

^isalso proportionallyhigher^tothe

summit

ofthefirst radials.

Locality

and

_position. Burlington, Iowa. Burlington Limestone. Collec- tion ofMr. Charles

Wachsmuth.

Genus CYATHOCRINUS,

^{Miller. 1821.}

Cyathocrinus

Wachsmuthi. Body

depressed, obconical, or subturbinate.

Baseofmoderate_{size, low,}

and

_distinctlypentagonal, ^the angles formed

by

the extremities ofthe plates a^littleincurved.

Columnar

facetcovering about one-thirdto one-fourth of each basal piece.

Column

_{obscurelypentagonal} near_{the base,} the _angles being

rounded

; central perforation comparatively large

and

pentagonal. Subradial_platesfiveor sistimesas large as thebasal pieces,aboutaslongas wide, three of

them

_hexagonal,

and two on

the anal sideheptagonal, ^allindented or incurvedat thesides

and

atthe

upper

angles.

First radials largerthan thesubradials,

unequal

ⁱⁿsize,

and

widerthan long^; allheptagonal,ⁱⁿconsequence^ofthetruncationofthe superior lateral angles apparently^forthe reception ofsmallinterradials,each having^theangles

below

distinctlyindented,

and upper

side truncated,

and

moderately concave^forthe reception of thesucceedingplates. Secondradialsvery^{short or}nearlylinear,

and

abouttwo-thirds aswide as the first. Third radials generally a little

narrower,

and

longer than the second,

and

_{apparentlytriangular} in form.

Sub-anal_piececomparativelylarge,quadrangular,

and

indentedatthe_angles;

firsttrueanalplate largerthan the sub-anal_piece,heptagonalin form, resting

upon

^avery^short

upper

^{truncatedside ofoneofthe} subradials,

and

connect- ing

on

eachsidewiththefirstradials; itsright inferior sloping side also^rest- ingagainst thesub-anal_piece.

The arms

after dividing

on

the third_radials, are strong

and rounded

ontheouterside; oneofthe divisions ineachofthe rays,exceptinganterior one, bifurcates again

on

the fourth piece. All the divisions

and

subdivisions are rounded, gradually tapering,

and composed

each^ofasingle series of pieces as longas, or a little longer

than

_wide,

and

giving ^{off at intervals of}

two

or three pieces alternately

on

opposite sides, rather strong jointed^lateraldivisions,

which

extend obliquelyoutwards

and

bifurcateseveral times.

The

surface

seems

tobe merelyirregularlygranulose.

On _examining

itclosely, however,^{traces of}very smallradiating slightly raised linesareseen

on

thesubradial

and

radial plates, as well asextending

up

^the

principal divisions of thearms.

We

take pleasureⁱⁿdedicating^thisspecies ^to Mr. Charles

Wachsmuth,

^of Burlington, Iowa,^to

whom we

areindebtedforthe use ofthe

specimen

^de- scribed.

Locality

and

_position. Burlington, Iowa. Burlington Limestone of the

Lower

Carboniferousseries.

Genus BTJRSACRINTJS,

^N.G.

(0vp<raapurse^; x/wvoca_lily, inallusion tothe purse-like form ofthe_typical species, asseenwithits

arms

folded together.)

[June,

NATURAL SCIENCES OP PHILADELPHIA. 137

Generic formula.

Basal_{plates, 5}?

Subradial_plates, 5; fourhexagonal

and

one pentagonal.

Radial_plates,

2X5.

Anal

_plate, 1.

Interradial_plates, none.

Arms,

10, bifurcating.

The

crinoid

upon which we

_propose^tofoundthisgenus, has

much

the _ap- pearance^ofanIchthyocrinus,with

which

_genusit

seems

toagree, exceptingⁱⁿ

having

^{truesubradial} plates,

and

but two, instead of three

primary

^radial plates ineach ray^{; alsoin} the possession^{ofa distinct}anal_plate.

Notwithstanding^itsgeneralsimilarity^to Ichthyocrinus, ^itsstructureis

more

nearly^likethat of Cyathocrinus,

from which

it differs

mainly

ⁱⁿ

having

^only two, instead of threeprimaryradial pieces ineach_ray,

and much

broader

and

flatterarms,

which

connectlaterally as inIchthyocrinus, so as ^toleave

no

in- terradial spaces.

Bursacrinus

Wachsmuthi. Body

^{below the}

summit

ofthefirstradial plates rather broad turbinate, or rapidly

expanding

from below. Base

unknown.

Subradial_{plates of}moderate_size, alittlewider than_long,

and

allhexagonal, excepting one

on

the anal _side,

which

is larger than the_others,

and

_hept- agonalⁱⁿform; theangles at themiddleofthe

under

side of each being^less salientthanthatabove. First radial platesabout one-third _larger than the subradials,near twice as wide as high,

and

all pentagonal, the

upper

^side beingtransversely truncated.

Second

radial pieces of the

same

size

and

form asthe_first, but invertedso as tobring the truncated ^side below; supporting

on

their superior sloping sidesthe firstdivisions ofthe arms,

which

_{are broad,}

flat,

and

connected_laterallywith each otherall around.

Anal

_piece rather small,longer thanwide, heptagonal, the angle ^at the middleofthe

summit

being

more

salient than the others; supported

upon

^{the short truncated}

upper

^{side ofoneofthe}subradials,

and

_connecting

on

eachside with thefirst

and

secondradial_plates,

and

the first of thebroad secondary^{radial or}

arm

piecesabove.

Afterthefirstdivision

on

the second radials, the

arms

bifurcate again

on

thesixth oreighthpiece, above

which

oneisseen to bifurcate again

on

the twelfth piece,

which

isasfarasthey can be^{traced in}the only specimenseen,

though

they

seem

tobe_long

and

_probablybifurcateonceoroftenerabove

Between

thedivisions

on

thesecondradial pieces,

and

thenext bifurcation above, they^areverywide, flat,

and composed

of short, slightlywedge-

formed

pieces,

which

aresquarely truncated

on

eachside.

The

nextdivisionsabove these are a little

more

than half as wide,

and composed

^{of a} single series of piecesbearing near the

same

proportions oflength

and

breadthasthose below.

The

surfaceisfinelygranulose,

though

^{there are}

no

traces of nodes, costse,or other prominences

on any

^oftheplates.

The

sutures are

merely

linear,and>

not impressed.

We

take pleasurein dedicating this interesting species, (the type^{of a}

new

genus,) ^to Mr. Charles

Wachsmuth,

of Burlington, Iowa,

who

discovered the only specimen

we have

seen.

Positionand_locality. Burlington Limestone. Burlington, Iowa.

Genus POTERIOCRINUS,

Miller, 1821.

Poteriocrinus? enormis.

Body

small, irregularlycup-shaped^{; sides}

some- what

_convex,

expanding

^{from the base; breadth} greater than the_height.

Base_small,spreading from the column, above

which

the_{plates are}seenpre- senting small pentagonal ^faces. Subradial _plates comparatively large,

un-

equal, hexagonal in form,excepting one

on

the anal _side,

which

is

much

larger than the others,

and

sub-heptagonal ^{in outline. First} radial plates

1861.] 10

138 PROCEEDINGS OF THE ACADEMY OF

larger than the smaller subradials, longer than_wide,

and

irregularly sub- hexagonal^orheptagonal^{; facet for} the reception ofthe secondradials small, not protuberant outwards, shallow

and

aboutone-third aswideas the_plates.

Arms

above thefirst radial piecesveryslender, cylindrical,

and composed

^of a single^seriesofsegments fromtwice to three or fourtimes aslong^aswide.

In

some

ofthe rays the^firstdivision takes place

on

thesecond, in others

on

the_third,

and

inthe anterior ray on the fourth piece above thefirstradials, after

which

_theybifurcate irregularly once, twice, or oftener,

on

the_second, third or fourth piece.

The

firstanal_plateis rather large,

and

rests

upon

^the

upper

^{truncatedside of}the largest subradial plate, so as to project considera- bly above the^first radials. Its left side curves inwards,

and

its right con- nectswith another_{plate of}nearly^its

own

size resting

upon

a sloping side of thefirstradial on the_right.

Above

theseareseenseveralother_plates,

which

form together^akindofslenderlateral trunk,or proboscis, rising like

an arm on

arange with the^truearms.

Some

^littledistance above, ^itcurvesinwith its

upper

extremity

between

_{the arms, leaving at}itsbase,

on

the_{left,a cavity} oropening, passing apparently^intothe

body between

^it

and

the first

arm on

that side.

The

surfaceisfinelygranulose,

and

the suturesindistinct.

The column

^is small, round,

and composed

^of nearly equal, rather short _joints, near the base.

A

_very

marked

feature ofthisspecies,^isitspeculiarity ofhaving apparently a slender proboscis

much

like

an

_{arm, rising} from the anal _side,with

an

opening

between

its left side

and

one of thearms. Thisisso

anomalous

a character, that^if

we

were sureitisnot

due

to

some

_accident,

we would have

regardedthe species asthe type^ofa

new

_genus.

Locality

and

_position. Burlington, Iowa. Burlington Limestone. Collec- tion ofMr. Chs.

Wachsmuth.

Poteriockinussub-impressps.

Body

^obconical. Base forming^ashallow

cup

abouttwice aswide as high,

expanding

moderately from the

summit

ofthe

column

;

composed

of plates

which

are aboutashighas wide,

and

_pentagonal in form, the angle^at

the

middleof the

upper

^{side of} each being^alittlein- dented. Firstradials

somewhat

smallerthan thesubradials, widerthan_long, pentagonal,^or

some

of

them

_hexagonal,

and

truncated

above

forthe_reception ofthesecondradials. First anal or sub-anal _plate, a little largerthan the basal pieces, pentagonal,

and

_resting

between

the

upper

sloping sides of

two

of thesubradial pieces; second anal_{piece of}the

same

sizeasthe_first, hex- agonalⁱⁿ form,

and

_resting

upon

^the

upper

^{truncatedside ofoneofthe sub-}

radials, whileitsleftsideconnectswith one of thefirstradials,

and

its right with oneside ofthefirstanal_piece,

and

with a thirdhexagonalpiece resting

upon

^it. (Succeeding parts

unknown.)

The column

is comparatively strong^{at its} connection with thebase,near

which

itis

composed

^ofrather thinsegments, connected

by

crenulated sutures;

itscentral perforation^isofmoderatesize

and

pentagonal.

The

surface

seems

to be _granulose,

and

the subradial_pieces

show

a very slighttendency^to develope ^{9hort costce}near the sutures on each_side,

and

below,as well as

sometimes

attheirconnection withthefirstradialsabove.

The round

indentations atthe angles^ofthe subradial

and

firstradial plates, present^{a rather}

marked

character inthisspecies.

Locality

and

_position. Burlington, Iowa. Burlington Limestone. Mr.

Charles

Wachsmuth's

collection*

Poteriockinus tenuibrachiatfs.

Body

small, calyculate, or turbinatebelow the

summit

of thefirstradial plates. Base _small,forming^alow pentagonal saucer-shapedcup,

composed

^{of small} plates,

showing

^a pentagonal ^outline abovethecolumn. Subradialplates ratherlarge,aboutaswideas long,three hexagonal,

and two

on the analside heptagonal,

and

alittlelonger than the

[June,

NATURAL SCIENCES OF PHILADELPHIA. 139

others. First radial plates

somewhat

_largerthan thesuhradials, wider than long

and

_pentagonal in form; facet for the reception of the secondradials moderately prominent, ^alittle concave,

and

from one-half to two-thirds the breadthofthe plate.

Anal

plates three, thefirst(orsuhanal_piece)hexagonal,

and

_resting

between

the upper sloping sides of

two

of the subradial pieces, whileanother

on

theleft restsagainstthis,

and upon

^thesuperiortruncated side ofoneof thesubradials.

A

third piece^is supported

on

the

upper

^trun- cated side of the subanal _piece,

and

_projects

more

thanhalf itslength above thefirst radial

on

its right.

The

succeeding

primary

radial pieces^afterthe

first,are distinctly smaller,

and

alittlewider than_long. Inallexcepting the anterior ray,

where

the bifurcationtakes_place

on

thefifthplate,thefirstdivi- sion of the

arms

takes place

on

the fourth

primary

^radial.

Above

this the arms,

which

are very long, slender

and

_rounded, divideagain

on

thefourth piece, ^after

which

the divisions bifurcate three or four times,

and become

very^attenuate.

Each

divisionis

composed

^ofa single^seriesof pieces, usually abouttwice aslong^aswide.

The

_proboscisconnects_directlywith the anal_platesalreadydescribed,

and

is

made up

^ofhexagonalplates, along the sutures ^ofwhich, ^distinct vertical ranges^ofrather large

and

distinctpores ^{are seen.}

The

entire surfaceisfinely granulose.

The

suturesare linear

and

not grooved^or impressed. This _spe- ciesissimilar to P. calyculatus of Hall,but

may

^beat once distinguished

by

itssuturesnot being excavated,

and by

^its

much more

slender arms,

which

are

composed

of elongate, instead of short

wedge-formed

pieces.

Locality

and

_position. Burlington, Iowa. Burlington Limestone. ^Collec- tionofMr. Charles

Wachsmuth.

Poteriocrinus carinatus.

Body

small, basin-shaped ^{or rather} rapidly spreading below the arms. Base verysmall,

having

^{the formofa}pentagonal star,the _{angles of}

which

_projectbut slightly

beyond

^the

column.

Subradial pieces small, aboutaswideas long, four of

them

hexagonal, (the

form

ofthe one

on

theanalsideisnot distinctly visible in the

specimen examined

^;)all ratherprominent,

and

provided with a^{vertical carina}nearthe

upper

angle.

First radial pieces abouttwice as large as the subradials, aswide again ^as high,

and

_{pentagonalin form,}the

upper

^sidebeingtruncated,

and

_longer

than

either ofthe others.

Second

radials slightly larger thanthe_first,wider

than

high, quadrangular,

and

alittleconstricted

around

the middle.

Thirdradials about thesizeof the _first,pentagonal in form,

and

like the second_slightlyconstricted, the

upper

angles being ^{rathersalient.}

The

anal plates arenotallpreservedⁱⁿthe specimenbefore us,

though we

canseethat thefirstorsubanal_pieceisof

moderate

_{size,pentagonal in form,}

and

extends sofar

down between two

of the subradials, as to connect (apparently)

by

^a very^shortside, with the

produced

extremity^ofone of thebasal pieces. ^Its rightsuperior sloping side supports oneedge ^of a firstradial above,

and

it

evidently supported another piece

on

its superior truncated edge, while it

connects

on

theleftwith another_resting

on

the

upper

^{truncatedside of}

one

ofthesubradials.

Afterthefirstdivision of the third radials

some

ofthe

arms

bifurcateagain on the_fifth,sixth or seventh piece, while others

seem

to be _simple.

They

areall

composed

of pieces

which

are a little constricted

around

the middle, aslong ^as wide,

and

alternatelylonger

and

shorter

on

opposite sides, the

upper

extremity^of the longer^{side of}each being a^littleprojecting^forthere- ception of the tentacles, so as^togive a zigzagappearance ^{to the}arms.

The

tentacles are_large,

and composed

of ratherlongjoints.

Owing

^tothe length ofthe

arm

_pieces,

and

the fact that onlyeveryalternate piece

on

the

same

sidesupports a tentacle, they^arevery widely separated

and

alternately ar- ranged.

The

surface

seems

tobe_granulose,

and

_{each ray}isprovided with^{a distinct} linear carina,

commencing

^onthe

middle

ofeach^firstradial piece

and

extend-

1861.]