Descriptions of New Cretaceous Fossils from Nebraska Territory, Collected by the Expedition Sent out by the Government under the Command of Lieut. John Mullan, US Topographical Engineers, for the Location and Construction of a Wagon Road from the Sources of the Missouri to the Pacific Ocean

NATURAL SCIENCES OF PHILADELPHIA. 21

Descriptions^of

new CRETACEOUS FOSSILS

from

Nebraska

Territory, collected

by

^theExpedition ^sentout

by

^the

Government

underthe

command

of Lieut.

John

_Mullan, IT.S. Topographical Engineers, ^for the location

and

construc- tion of a

Wagon Road from

^{the sources of the Missourito the Pacific}

Ocean.*

BY

F. B.

MEEK AND

^F. V.

HAYDEN.

The

collectionscontaining ^thefossils describedin thispaper,

were

obtained along^{the Missouri}Riveratvariouslocalities

between

Fort Benton

and

_points 140to 150 miles belowthe Fort.

The new

forms hereforthe firsttime

made known,

^{arealllabelled "}

Chippewa

Point,"

which

is

some

_twenty

odd

miles

below

FortBenton. Thereare alsointhe collectionfromthis locality,

and

_ap- parentlyfromthe

same

_rock,

some

finespecimens ^ofour Inoceramus umbonatus

and

/.fragilis, Hall

and

Meek.

The

_presenceof the latter species,

and

the affinitiesof several of the

new

forms, indicate thatthesefossils all

come

from No.2 ofthe

Nebraska

Cretaceous _series,

which

is

known

to be extensively developedⁱⁿthat region: fragments^ofoneor

two

of the

new

_{species atleast,} have_certainlybeen foundinthathorizonatother places.

As we have

nosec- tionof the strata exposed^{atthis locality,} however,

we

are withoutthe

means

of

knowing

^whetheror not these fossils all

came

from the one bed. Iudeed,

some

of

them

_beingquite peculiar,

and

_very unlike anything ^hitherto

known

in our

Nebraska

series atother localities,^itisbarelypossible there

may

^bea

member

here of the Cretaceous not previously recognized elsewhereinthis region.

There are alsointhe collectionfromthe

same

place as theabove,^a

number

of

good

specimens^ofAtrypareticularis; they ^{are labelled "}

Chippewa

Point, 300feet above the level of theriver." Theseare of

Devonian

or

Upper

^Silu- rianage,

and were

doubtless broken from boulders, or other ^erratic masses, brought by^driftagencies from

some

distant northern _locality,

and

of course

have

no connection with thegeology^ofthisimmediate_vicinity.

At

another_locality, ninety milesbelow Fort Benton, ^aspecimen^of our Tan- credia Americana,

and

afew other bivalves,were obtained,

though we

donot

know whether

_they

were

foundin situ or loose.

They

evidently belong ^tothe

same

beds occurring^atthe

mouth

ofJudith River, fartherup,

which we have

elsewhere referred with doubttothe

Dakota

_Group,(No. 1) of the

Nebraska

Cretaceousseries.

That

thisbedisCretaceous,^isproved by^theoccurrencein itof ofBaculites,as well as by^{the affinities ofits other fossils,} excepting^the Tancredia,

which would

alone _pointto alower horizon. Itsexact position^ir.

theCretaceousseriesstillremains doubtful.

The

collection also contains from other places 125to 150miles below Fort Benton, specimens^{of Oslrea}sublrigonalis,

Evans and Shumard, and

^{of thefol-} lowing species elsewhere described by^{us: Corbicula} [Cyrena]cytheriformie, Corbula_{permidata, Vivipara}Conradi

and

V. trochiformis; allof which belong^to the Fort

Union

Group, (brackish water

and

lower _Tertiary deposits) of that region.

Some

of these

were

probably obtained from^loosemasses.

Good

speci-

mens

of Baculites compressus, Say,

were

likewise collected near oneof these latter localities.

Figures

and more

extended descriptions of the

new

species here indicated aretobe prepared

by

^{us for}publication in Lieut. Mullan's^finalReport.

*

The

fossilsdescribed in thispaper werecollectedby Mr.JohnPearsall,

who

acted as naturalistofLieut.Mullan'sexpedition.

1862]

THE ACADEMY OF

CEPHALOPODA.

Genus SCAPHITES,

^Parkinson.

SCAPHITES VENTRICOSUS.

Shellventricose,attainingarather largesize,oval-subgloboseⁱⁿform,broadly rounded onthedorsum. Umbilicus very small,deep,

and showing

scarcely

any

part of the inner whorls. Volutions aboutthree tothree

and

a_half,increasing rather rapidlyin size,particularlyⁱⁿbreadth, nearly twice aswide transversely asfromthedorsalto the ventral side; ^allregularly rounded on each^side

and

deeply embracing ^{within; last} one deflected from the regular curveof the others so asto

become

_slightly disconnected at the aperture,

which

istrans- versely reniformor lunate. Surface

ornamented

with

numerous

small, rather regularcostas,

some

forty-five to fifty-fiveof

which may

^becounted aroundthe

dorsum

ofeach _turn,

where

_theyare ofuniform_size, excepting ^theirgradual

and

uniform enlargementwith the whorls.

On

the outer, or^lastvolution, only every^{fifth or sixth} oneof thecostse extends across totheumbilical margin^; the intermediateones

becoming

^{obsolete onthe} sides,

where

those extending entirely across

become

_larger,

more

_prominent

and more

angular than on ^the dorsum.

The

_{septa are} each provided with^five deeply-divided principal ^lobes.

The

dorsal lobeislonger than wide,

and

has oneach sideofits very ^slender

body

three

main

_branches, the

two

terminal of

which

are slightly largerthanthe next_{pair above,} and each provided with three orfour small unequal ^subdi- visionson the outer side.

The

dorsal saddle is as large as the dorsal _lobe, extremely

narrow

atits base

and

profoundly ^{divided atits}extremity into

two

unequal branches,^ofwhich theone onthe dorsal sideislargerthanthe other,

and

_distinctlytripartite,eachofitssubdivisions being deeply sinuous

and

ob- tusely digitate.

The

other

main

branchis very narrow,

and

_provided with several _short, obtusely rounded, irregular ^{lateral divisions.}

The

_superior

lateral lobeisaswide as the dorsal lobe,but _shorter,

and ornamented

with

two

_large, nearly equal bifurcating terminal branches, the ^lateral subdivisions of

which

arebifid and

more

orless digitate,whiletheother

two

areeach_pro- videdwith from fivetoseven digitations.

The

lateral saddleis

much

smaller thanthe dorsal saddle, verynarrowatitsbase,

and

consistsaboveof

two

_equal trilobateterminal branches.

The

inferior lateral lobeis little

more

than one- third as large as the superior,

and

_{very similarly divided, excepting} that its

branchesare proportionally shorter.

The

ventrallobeisvery^small

and armed

withthree or four_short,simple^divisions.

Length,

313

inches; height, ²65 inches; breadth or convexity, 1-90 inch.

In itsexternal ornamentation, ^{this shellis}

much

likea species described

by

usfrom neartheBlack _Hills, underthe

name

ofS. Warreni, (Proc. Acad.Nat.

Sci. Phila.,May, 1860,p. 177.) ^Itdiffers, however, remarkably ^{in size}

and

form, beingnearlytwenty^{times aslarge,}

and

proportionally

much more

ventri- ccse, whileitsvolutions increase

much more

_rapidlyin size. Itsumbilicusis also proportionally smalleranditsbody whorlnot deflected sofarfrom thecoil of the inner turns.

As we

have _{not yet}

had

an opportunity^tosee the septa of S. Warreni,

we

have no

means

cf

knowing how

_nearly these foinis

may

agree intheir internal structure.

Localityand_position.

Chippewa

Point,nearFortBenton, on^the

Upper

^Mis- souri; FortBenton

Group

^{of the}Nebraska Cretaceousseries.

SCAPHITES VERMIFORMIS.

Shell attaining a

medium

_size,oval subdiscoidalinform. Umbilicus very small. Volutions _increasing gradually ⁱⁿ size, rounded on the

dorsum and

sides,and deeply embracingwithin; ^allalittlebroadertransverselythan from the dorsaltothe ventral side; lastonedeflectedfromthe regularcurveof the others, so as ^to

become

_slightly disconnected at the aperture,whichistrans-

[Feb.

NATURAL SCIENCES OF PHILADELPHIA. 23

versely subreniform,or alittle oval,witha

somewhat

sinuous inner margin.

Surface

ornamented

_by

numerous

_{straight costae,}

which

aresmall

and

_nearly regularonthe inner volutions, but

become more

_irregular

and

_larger on the side^ of the

body

whorl,

where

_theysupport around each dorso-lateral region, a

row

ofprominent nodes^sodisposedasto alternateonopposite aides of the shell.

On

the

dorsum

the costs are ofuniform size, with the exception^{of their} regular enlargement with ^{the whorls.}

The

nodes are directed out at right anglestotheplane^{of the} shell, and,^likethe_costEe,

become

_againsmaller

and more

_{closelyarranged towards} the aperture.

Some

of thecostae bifurcate at thenodes onthe

body

whorl, but ^their

number

isalsoincreasedby^{the inter-} calation of others between.

Where

they bifurcate at

any

^{of thenodeson one}

side,the twodivisions crossingoverthe

dorsum

from the point of bifurcation, never both intersect a

node

on the opposite side,but,ⁱⁿ

most

_cases, one of them,

and

sometimes _both,terminate

between two

of thenodes ontheother side. In crossing over the dorsum, near the aperture, they ^all curvealittle forward, but on other parts of the shell they pass nearly or quite straight across.

Tne

_septate portion of the only specimen^{of this} speciesⁱⁿ the collection being highlycrystalline,the sutures ofitssepta cannot be very clearly traced out.

We

can_see,however, thatthe dorsallobeis alittlelonger than ^{wide. It} has a rather

narrow

_body,

and

isprovided with ^three branches on eachside, the upperpair of

which

are small

and

nearly simple,whilethe next_{pair are} longer

and

bifid,andtheterminal_pair,

which

arealittlelargerthanthesecond, areeach

ornamented by

^three small, pointed branches or digitationsonthe outer side.

The

_superior lateral lobeis

somewhat

irregularly tripartite,the lateral divisions being ^bifid

and

_sharplydigitate, while the terminal,

which

i3 longerthan the others

and

not exactly central, has about five pointed digita- tions,or sharp, nearly or quitesimple branchlets.

The

lateralsaddle is deeply dividedattheextremity^into

two

_nearlyequal branches.

The

inferior lateral saddleisnot

more

than aboutone-third as large as the superior, nearly as long as

wide

and _regularlytripartite,while the others have about four digitations each,

and show

a_slightdisposition ^tobifurcate.

Length,2-10 inches; height, ^1-76 inch; greatest breadth measuring^tothe extremities of thenodes on_{oppositesides,}1-25inches; do.between_{the nodes,}

1 inch.

This _species isrelated to S. hippocrepis of Dekay, sp.

(=

^Ammonites hippo- crepis, Dekay, An.^{N. Y.}

Lyceum,

^{vol. ii.}pi. v.fig. 5,) but differs in having^its

body

^{whorlless extended}

away

^{from thecoil}of inner volutions,

and

inbeing higherⁱⁿproportion ^toitslength. ^Itsnodesare also larger

and much more

prominent; but^the

most marked

difference

between

these

two

formsisintheir septa, the dorsal lobe of that under consideration being proportionally

much

narrower

and

_providedwith three instead of

two

branches on each_side; while

itslaterallobes are distinctlytripartiteinstead of bifid.

It is also allied to S. Texanus, Roemer, (Kreid.

von

_Tex., tab. _{1, fig.} 4.) though ^itssepta^differaswidely fromthose of thatshell asfromS.

hippocrepis.

Itssmaller_{size, less} ventricose form, narrower _whorls, and distinct nodes, will atoncedistinguish ^itfrom the last described _species, with

which

it

was

foundassociated. Itssepta also^{differ in} the _tripartite character of itslateral lobes,

which

is an unusual feature in thisgenus.

Localityand_position.

Same

aslast.

Genus AMMONITES,

Bruguiere.

Ammonites Mullananus.

Shell compressed-subglobose;

rounded

on the dorsum. Umbilicus _small, deep

and

_{acutely conical,}

between

one-third

and

one-halfas wide as the

1862.]

ACADEMY

breadthof the outerwhorl fromthe dorsalto the ventral side,

showing

^about one-third ofeach inner volution.

Whorls

increasing rapidly^{iu size,} particu- larly atright angles^tothe plane of theshell, slopingon eachsidefrom near theumbilicus_{(with a}slightlyconvexoutline)towards thedorsum,

and

round- ingabruptly^intotheumbilicusonthe ventral side;eneh of those within deeply

embraced

_bythesucceeding^turn. Aperturetransverselyreniformorsublunate.

Surface ornamented with rather small, regular, rounded costse,

which

_pass nearly straight across the sidesof the whorls,

and

arch _slightly forward in crossing overthedorsum.

On

the dorsal_side, (where they^{are of}uniform_size,) fromthirty-six^toforty of the ^costa3

may

^{be counted to} every turn.

Each

of those

commencing

^{attheumbilicusis}there usually a^littleenlarged, especially on the larger whorls, so as^toforma small, subnodose prominence.

Beyoud

these they^all(particularlyon the innerwhorls)bifurcate regularly once,near themiddleof each side,

and

onthe larger turns others are also intercalated between,^{so as to}

make

the

number

on the dorsal side five orsix times as great asat the umbilicus.

The

_septa are rather

crowded and

provided with variously branched

and

deeply sinuous^lobes

and

saddles.

The

dorsal lobe isabout one-fourth longer than wide, nearly obovate in form,

and ornamented

with three principal branches on eachside,the

two

terminal of

which

are larger than the others

and

each provided on ^{the outer side} with

two

or three

more

orless digitate lateralbranchlets,whiletheinner_parallel margins^aremerelysharply serrated.

The

dorsal saddleisofaboutthe

same

sizeasthedorsallobe, alittleoblique, nearly oblongⁱⁿform,

and

divided at the extremity into

two

tripartite

and

obtusely digitate branches, of

which

theoneonthe dorsal sideislarger than the other; belowtheseitisprovided on each ^sidewith

two

alternating^lateral branches with sinuous margins.

The

_superior lateral lobe is narrower

and

shorter than the dorsal _lobe,

and

provided with

two

_principal branches on eachside,the

two

terminal of

which

are

much

_larger than the others,

and

of unequal ^{size, the} oneonthe right or dorsal side being ^the larger. Bothof these terminal branchesare_{distinctly bipartite,}the subdivisions being orna-

mented

withseveral branchlets

and

smaller digitations.

The

lateralsaddleis

abouthalf as wide

and

near two-thirds aslongas the dorsal saddle,

more

or less oblique and rather deeply divided at the extremity into

two

subequal, bifurcatingand_{obtuselydigitate} terminal branches.

The

inferior laterallobe isaslong ^{as the lateral} saddle, butalittle narrower, and ornamented with three variously digitate terminal branches,^the middle oneof

which

islonger thanthe others, a^little oblique

and

not exactly central.

The

ventral lobeis small,being ^{less than half as} long,

and

_scarcely two-thirds as wide, as the inferior lateral lobe,

and

_provided with three nearly equal, spreading, digi- tate,terminalbranches.

Between

the ventral lobe and the umbilical margin there are

two

small auxiliary lobes,thefirstof

which

has

two

or three _digi- tationson each side; while thesecondis nearly simple, orbut_slightlysinuous onthemargins.

In the

number

and arrangement^{of thelobes}andsaddles ofitssepta, as well asin their

mode

of branching,^this species agrees very nearlywith A._Ilalli,

(Meek and

Hayden, Proceed. Acad. Nat. Sci. Phila.,March, 1856,p. 70.) ^It has, however, one

more

lateral branch on eachside of i'sdorsal_lobe,

and

one less on each ^{side ofits} superior ^lateral lobe, than A. Ilalli; whileallthedi- visions of^its lobes

and

saddles are

more

_spreading.

Although

^so closely allied in theirinternal characters, these

two

shells present

marked

differences inform, as well as ⁱⁿtheirexternal markings,the species

now

underconsidera- tion being

much more

ventricose

and more

coarsely ribbedthan

A.

Ilalli.

Itagrees

much more

_nearly inform with A._Barnrtoni, Meek,(Prof. Hinds' Report,Assiniboine

and Saskatchewan

Expl. Expedition, pi. 11, ^{figs. 1}

and

_2,) fromfarupnorth, on Mackenzie's ^River; but differs inhaving^{a smaller}

and

[Feb.

NATURAL SCIENCES OF PHILADELPHIA. 25

more

acutely conical umbilicus,

and

less broadly

rounded

dorsum. Itscostae are also

more

_rounded,

and

itpresents well

marked

differencesinitssepta.

The

_onlyspecimenof thisspecies

we

haveyet seen consists entirely ofsep- tatewhorls, the non-septate outer portion having been broken away. ^It

mea-

suresinitsgreatest,diameter_{4 inches,}

and 257

inchesin breadthatthewidest part of the outer whorl.

Named

inhonorof Lieut.

John

_Mullan, TJ.S. Top. Engrs., ⁱⁿ charge ^{of the} Expedition^forthe location

and

construction of the Pacific

Wagon

^Road.

Locality

and

_position.

Same

as preceding.

Genus NAUTILUS,

Breynius.

Nautilus elegans, ^var. Nebrascensis, Nautilus_elegans,

SowerbyJ^816.

^Min. Conch.,pi. 116.

Nautilus_elegans,Mantell, 1822. Geol. Sussex, ^t.xx._fig.

Nautilus_elegans, D'Orbigny, ^{1840. Palaeont.} Franc.Ter. _Cret.,t. i.pi. 19.

Nautilus_elegant, Sharpe, ^{1853. Foss. Mai.}Chalk,pt.1,Ceph.pi. 3, fig.3,

and

_pi.

4, fig. ^1. Palaeontographical Society.

Shell globose, broadly

rounded

over the

dorsum and

_sides; umbilicusen- tirely closed; volutions increasing rapidlyin size,considerably wider ^trans- verselythanfrom thedorsal tothe ventral side; aperture transverselyreniform or subluuate,being deeply sinuous on the inner side for the reception of the preceding^turn; marginsof the septa rather abruptly arched forward near^the umbilicus,

and

_slightly

backwards

on the dorsal _side, deeply concaveon the

outer side

; siphuncle ^located about its

own

breadthoutside ofthe middleof each septum. Surface of the

body

^whorl

ornamented

_{by regular, flattened,} transversecostaeaboutfivetimes asbroadasthegrooves between. In crossing overthe dorsum,^{thesecostae all} arch_gracefully

and

_deeply

backwards

_parallel tothebroaddorsal sinus of the_lip.

On

the inner whorls, the ^costse

become

obsolete or are only representedbyrather distinctlinesofgrowth.

Length

or greatest diameter, 3-90 inches; height, 2-82 inches; breadth, 3-40 inches.

This shell agrees almost _exactly, in form

and

surface markings, with Mr.

Sharpe'sfigures ofSowerby's species,^to

which we

have referredit,

and

_only

differs in having ^its siphuncle^alittle

more

_nearly central

and

itsumbilicus closed,apparently^atallages. According^{to Mr.}Sharpe, ^the umbilicusof

N.

elegans^isclosedinthe

young

shell,but

becomes

alittleopen^{inthe outer}whorl of largespecimens.

He

also statesthatitssiphuncle^islocatedabout half

way

between the middle

and

the dorsal sideof the septa,

though

ⁱⁿhis'figureon plate 4 of^his

Mouograph

^citedatthe

head

of this description,^{it is} represented

somewhat

nearer the middle.

Such

smalldifferences,howevtr,

we

can_scarcely regardasbeing^of specific importance,but, ^iffullercomparisons should prove ourshell to be_distinct, itcanretainthe

name

of Nebrascensis.

It is

worthy

^{of notethat}D'Orbigny'sfigures citedabove represent arather distinctly ^lessventricose form, with a

more

_narrowly

rounded dorsum than

our

Nebraska

_shell,orthose_figured

by

Mr. Sharpe.

He

also

shows

a distinct longitudinal ^line

on

themiddleof the

dorsum

(of

an

internal cast)not seen

on

our specimen, nor

on

those_{figured in}Mr. Sharpe's

Monograph.

Dr.

Shumard

hasdescribed, in^vol.i. p. 590ofthe Transactionsof the St.

Louis

Academy

^of Sciences, a similar species

from

the cretaceous rocks of Texas.

As he

_{mentions, however,} that the siphuncle^of the

Texas

shell is situated

between

the middle

and

theventral side of the_septa,

and

that the height^{of its}aperture^is greaterthan its breadth,

he

doubtless hasa distinct speciesfrom

N.

_elegans. Sofaras

we know,

this is thefirsttime Sowerby's specieshas

been even

_doubtfullyidentified inAmerica.

Locality

and

position.Sa.mQas preceding.

1862.]

PROCEEDINGS OF THE ACADEMY OF

LAMELLIBRANCHIA TA.

Genus INOCERAMUS,

Sowerby.

INOCERAMUS UNDABUNDUS.

Shell _(leftvalve) obliquely rhombic-subovate, gibbous, anterior sidevery short, obliquelytruncated

from

the

beak

_above,

and

_rounding into thelono- antero-basal

margin

^; base very prominent,

and

_abruptly

rounded

a little

behind

the middle,

from which

_point its

margin

ascends obliquely forward withagently

convex

outline; posterior sidebroadly

rounded

orsubtruncate;

dorsal outline sloping fromthebeaks at

an

_angle ofabout 90 ; hinge appa- rently short;

beak

moderately prominent, incurved,

and

directed a little

towards the front;

umbonal

axis ranging ^at

an

_angleofabout 70 with the hinge ^line; surface

ornamented by

regular, distinct, concentric undulations,

which

are(on thecast)subangular,

and

_separated

h*

shallow

rounded

_depres- sions; shell structure coarsely fibrous near the _fnnge. (Right valve un-

known.)

Height from the

most prominent

part ofthe base tothe hinge, 3 inches;

length^atrightangles to height, 3inches; convexity, 1*84 inches.

The

_{peculiar obliquely}

rhombic

outline, rather gibbous form,

and

_regular undulationsofthis shell, will readily distinguish ^it

from any

^other species

known

to us. It is true, bcth the following species

have

the corresponding valve

more

gibbous than this,but in those the _greatestconvexity^{is in}the

umbonal

_region, whilein thisitisnear the middleofthevalve. Inallother respectsthey^are

remarkably

^unlike.

Locality

and

_position.

Chippewa

Point,near Fort Benton,

on

theMissouri River, from beds

supposed

^{tohold the} position ofFort

Benton Group

^ofthe

Nebraska

Cretaceoussection.

INOCERAMUS EXOGYROIDES.

Shell large^{; left}valvesubcircular,^itsheight being ^alittlegreater

than

its length fromthe anterior tothe _{posteriorside,} very gibbous^; buccal

and

anal margins rounded,

and

forming with the base aboutthree-fourths ofacircle;

cardinal border

somewhat

arched;

beak

_{large, elevated, gibbous, distinctly} involuted

and

directed obliquelyforward, so as to bring ^its point near the anterior

margin

^; surface of cast smooth, ^or

marked by

^obscure concentric- folds. (Right valve

unknown.)

Length

^from anterior to posterior margin, ⁵ inches; height, 5*50inches;

convexity near^{3 inches.}

We havenotyetseen therightvalveofthisspecies, but judging from the gibbouscharacterandincurvedbeakof theleft, itwill probably be found to bemuch morecompressed,so astomakethe shellverydistinctlyinequivalve.

The

_{laterallycurved}

beak and

_generalformoftheleftvalve_giveit

much

the appearance^of

some

species of Exogip-a,

when viewed

on the innerside. Its apertureis transversely oval, the height being ^tothe length about^{as four to} five.

Remaining

portions oftheshell aboutthehinge

show

it to

have

been rather thick

and

_distinctlyfibrous.

This _speciesdiffersfrom an analogous form described

by

usfrom the

same

position^?(and from near the

same

_locality)

under

the

name

of I. tanbonatus, in being

much more

_depressed,

and

inhaving ^its

beak

considerably^{less ele-} vated, as well as directed

much more

_obliquely forward. In 7. umbonatus

(some

finespecimens^of

which were

broxight inwith the form

under

considera- tion) the

umbo

of the leftvalve rises near one-halfthe entire height^ofthe shell above_{the hinge,} whileinthe species

we

are here_describing it extends less than one-third the height^ofthe shell above.

The

_length ofthevalve from theanterior totheposterior side^isdistinctly greater inproportion^toits height than^inI. umbonatus, while the corresponding valve^ofthe latter shell is

much more

_gibbous.

We have beforeusaseriesof specimens belonging toeachof these forms,andfindnodifficultywhateverin separatingthem.

[Feb.

NATURAL SCIENCES OF PHILADELPHIA. 27

A

carefulexaminationof

much

betterspecimens^of/. umbonatus, inthecol- lections

now

_{before us,}thanthat firstdescribed

by

us,

shows

thatformto be

even more

closely allied to^/. involutus of

Sowerby than we had

at first sup- posed.

As

_{Sowerby'sspecies}holdsa position, however, ^inthe

Upper

_Chalk,

and

ours

comes mingled

^with

Lower Chalk

_types, it is probablea

comparison

of perfectspecimens^ofeach

would

result in thediscovery^ofconstantdiffer- ences.

Locality

and

_position.

Same

as last?

Inoceramus

tenuirostratus.

Leftvalve verygibbous,subquadrilateral^inoutline;anterior sidetruncated almost immediately^{in frontof} the beak,

and

_rounding intothe basebelow;

ventral

margin

semielliptical in outline^;posterior siderounded, ^or

sometimes

subtruncate

above

; hinge straight, comparatively long,

and

rather finely crenulated, therebeing about^fivecrenulations inthe space^{of -}20 inch;

beak

verygibbous, pointed, slender, prominent,

and

_{distinctlyincurved,} directed obliquelyforward so as to bring ^its point nearly overthe anterior

margin

^; surface (of internal cast)

smooth

over the gibbous

umbonal

_region,but

having

afew small

and

very obscure^concentricundulationsbelow the middle. (Right valve

unknown,

but probably compressed.)

Length, ^2*10inches; height

from

base to hinge, 1 '82inches; height

from

base_{to top of}

umbo,

^2-13inches; convexity, (leftvalve_only,) ^-90inch.

This shell has a longer hinge

and

a

more

transverse

form than any

^other species

known

_{to us,}

having

soprominent, slender,

and

incurved a beak. It differs

remarkably from

^thelast, inthe slenderness ofits

beak and

lessregu- larly ventricose character of its left valve. Its

umbonal

_region ^is

perhaps more

_gibbous

than

that of the_last,

though

^this gibbosity^is

more

local

and

abrupt.

Locality

and

_position.

Same

aslast.

Genus VENILIA,

^Morton.

Venilia Mortoni.

Shell transverselyoblong, or

subrhombic

in outline, gibbous, thick

and

strong^;base nearlystraight, but rounding

up

^{infront;dorsal}

margin

parallel tothebase, excepting behind,

where

itroundsintothe anal

margin

^;anterior sidetruncated immediatelyin front ofthebeaks; posterior

margin

^truncated a littleobliquely^; postero-basal extremity abruptly

rounded

or subangular^; beaks located directlyover the anterior margin, ^directed obliquely forward,

and

rather distinctlyincurved at the _{points, as} in Isocardia; posterior

um-

bonal_slopesforming^a

prominent

oblique ridgefrom each

beak

tothe_postero- basal extremity^; lunule

and

escutcheon impressed, but without _distinctly defined

margins

^{; surface}

marked

with strong ^lines

and more

or lessdistinct concentric ridges ofgrowth,

which

latter

assume

_{a regular}

arrangement on

^the

umbones.

Length,^1*66inches;height, ^l

-40 inches; breadth^orconvexity,1*17 inches.

This _speciesisalliedtoVeniliaConradiofMorton, (Synop.Org.

Rem.

_pi. 8, fig.

12,)

^but differs, ^if Dr.Morton's _figures are correctlydrawn, ⁱⁿ being proportionallylongertransversely,

more

nearly oblongin form,

and

in

having

itsposterior

margin more

distinctlytruncated,whileits antero-ventralregion

islessprominently rounded. ^Itsdorsal

margin

^isalso

more

_nearlyhorizontal,

and

roundslessregularly intothe truncated analborder.

The

_genus Venilia

was

_proposed

by

^Dr. Morton, in 1834, ^forthe _reception of a rather peculiar shell,

which D'Orbigny

^afterwards referred to Cyprina.

We

agree,however, with those authors

who

_regard itas clearly distinct

from

the_typicalformsof Cyprina,

though

^it

may

^{not be}generically distinctfrom a few forms referred

by some

^tothatgroup.

We have nothad anopportunity 1862.]

THE ACADEMY OF

to see Dr. Morton's _original specimen, but, judging from his figures

and

a carefully

drawn

sketchofitshinge^sentus

by

Mr. Gabb, ^it

seems

tous

more

nearly^{allied to} Cypricardia of

Lamarck

thanto Cyprina.

The

only question ⁱⁿregard^to thepropriety of retaining Dr. Morton's

name

arisesfrom thefactthatit

had

been previously (1829) applied

by Duponchel

toa

group

of lepidopterous ^{insects. If} Dupouchel's

genus

^isagood one,

we

think Morton's

name

forthe groupof shells to

which

the_species

under

con- sideration belongs should be changed, although

we

are aware

many

^natural-

ists are inclined toadmittheuseof the

same

_generic

names

indifferentde- partments^of Natural_History.

Locality

and

_position.

Same

as preceding.

Genus PHOLADOMYA,

Sowerby.

Pholaoomya

papyracea.

Shell rather

under medium

_{size, extremely}thin

and

_fragile,transversely subovatein outline, moderately

convex

intheanterior

and umbonal

_regions, cuneate

and

alittle gaping behind; outline of base _regularlysemiovate, ^its

most prominent

partbeing

somewhat

inadvanceof themiddle; anterior side short

and rounded

; posterior

margin more

narrowly

rounded

; hinge

margin

straight, long, not inflected so as toforma distinctescutcheon; beaks

mode-

ratelygibbous, rising ^little above _{the hinge,} incurved

and

located near the anterior extremity^of the _shell, but not terminal. Surface

ornamented by

about twelve small_{radiatingcostse,}

which

are interrupted

by numerous

small, regularlyarranged^concentricridges.

The

_radiating costsearedivided

by

^the concentric _ridges, so as to present ^the appearance ^of rowsof

minute

nodes placed

upon

^{the latter.}

The

surface

markring

^{are all} distinctly impressed

upon

the internalcast.

Length, ^1*16inches; height, 0*76inch; breadthorconvexity, ^{0-55 inch.}

This_speciesseemstobe closely allied toPholadomyaoccidentalisofMorton, (SynopsisOrg.

Rem.

_pi. viii.fig.3,)butis

much

_smaller,

and

differs inhaving

numerous

regular concentric ridges, separated

by

^{furrows that} completely divide the radiating costse,

which

are less

numerous and more

_regularly arranged than on Morton'sspecies.

It also resembles P.ovulum of Agassiz, (Etud.Crit. surles Moll. Foss. tab.

36, fig. 1 6,)anOoliticspecies,but has_{a longer}

and

_straighterhinge margin,

and

differs in being ^{destitute of} a distinctly defined depression along ^the dorsal margin. ^Itsconcentric ridges likewiseappear^{to differin} being

more

regular

and

distinct.

Locality

and

_position.

Same

as preceding.

Monograph

^ofthe Species of

SPH2ERIUM

of

North and

South America.

BY TEMPLE PRIME.

(Continuedfrompage409,Dec,1861.) 15. Sph.

triangulare,

Say.

Cyclastrianyularis, Say,

New Harm.

Dissem._{356, 1829.}

Animal

not observed. Shell transversely oval, nearly equilateral, rather full, anterior

margin

slightlydistended, rounded, posterior

somewhat

_abrupt, nasal

rounded

; beaks _{large, full,}

prominent

^{; lines of}

growth

regular, epi- dermis brownish; hinge

margin

narrow, curved;cardinal teethverydistinct,

assuming

^theshape^oftheletter

V

reversed; lateralteethprominent.

Long.^{9-16; lat. 7-16;} diam.4-16 inches.

Hah.

N. America,ⁱⁿMexico. (Cabinet Acad. ^Nat. Sci.Philada.)

The

specimens from

which

I

have

_prepared this description

were

_presented

tothe

Academy

^ofNaturalSciences ofPhiladelphiabyMrs. Say, as theCyclas

[Feb.