PROCEEDINGS

Vol. XXI, ^pp. 125-136 April _11,

1908

PROCEEDINGS

OFTHE

BIOLOGICAL SOCIETY OF WASHINGTON

NEW GENERA OF UNSTALKED CRINOIDS.

BY AUSTIN HOBART _CLARK,

United States Bureauof Fisheries.*

Some time ago

^I

published

^{a revisionofthe}

genus

"

Antedon "

as

understood

_bj"

Dr.

P.

H. _Carpenter and most modern workers upon

the Crinoidea, ⁱⁿ

which

I

divided

the

group

^into eighteen

genera

ⁱⁿ

an attempt

^{to better}

bring out

the relation-

ship

^of the various _specifictypes.

The material

at

hand

at the

time was

not

very

extensive,

and

I

was

forced to leave certain genera,

most

especially

Antedon

(as restricted), in a

somewhat

unsatisfactory

condition

;

although

^{IrealizedthatI}

was "

lump- ing"

certain well-defined generic

types under a

_{single generic}

name,

^{I did}

^not

^feel justified in

making any

further subdivis- ions.

Further study and more abundant

material

have shed

much

_light

_upon many ^obscure

points,

and

I

am now

able to

point out

certain additional,

apparently well-marked and homo- geneous,

specific groups.

My previous paper contains one

^or

two

_errors,

which

I

take

this

opportunity

^of correcting; the

pinnules

^of

Calometra

are said to be cylindrical,

whereas

in _reality

they

^are

sharply

^trian- gular; ^this error arose

from _having

studied

only wet

_material,

whereas

a true ideaof the charactersofthe

Comatulida _{can only} be

ascertained

from

dried

specimens;

^I

followed Carpenter

ⁱⁿ

placing Antedon

^{diihcni of}

Bohlsche near Antedon

_bifida, in

my

restricted

genus Antedon

; it is,

however, merely

^the

young

^of

Tropiometra carinata;

Antedon

tenuicirra of

Carpenter should have been placed

ⁱⁿ

Thysanometra

; it is possibly the

young

^{of T.}

U nelloides,

but

further material is

necessary

^before

they can be united with

_certainty; the species compressa

and

_orion,

_placed

*Published by permission^{of the}CommissionerofFishandFisheries.

17—Proc. Biol.Soc.Wash.,Vol. XXI,^{1908. U'.tf)}

126

Clark

— _{New Genera}

_{of UnstalkedCrinoids.}

in Charitometra,

should have been

referred to Thalassometra_; the

Antedon

_flava of

Koehler and

the

Antedon

_porrecta of

Carpenter (which were omitted)

also

belong

^to Thalassometra. I

had not been

able to consult Professor Bell's

paper on South African

crinoids,

although

^I

had examined _specimens

of his capensis;

ofthe

two other

_{species described,} sclateri belongs ^to the

genus

Charitometra

(near

C. insequalis)

and _magnlcirra

to Thalassometra.

Family HIMEROMETRULE.

Oligometra

gen. nov.

Genotype.

—

Antedon _serripinna P.

H.

_Carpenter, 1881.

Centro-dorsal_{flat, discoidal,} the cirrimarginal, ⁱⁿ one ortwo

more

or less irregular

and

crowded rows. Cirri short

and

_stout,

composed

^of few, twenty ^{or less} (rarely one or two more), squarish or short joints;

the opposing spine central ⁱⁿ position

and

short; the distal joints

may

bearcentrally situated spines, paired spines, or tubercles. Radials

more

or less concealed; ^costals rounded, broad,

and may

^or

may

^{not he in}

apposition laterally.

Ten arms

of rather short, wed<je-shaped joints, becoming oblong distally. Proximal pinnules rather stouter

and

stiffer

thanthe _others, hut not _especially

marked;

^{one or}

more

_elongate, hut

little,ifany, longerthan thedistal pinnules; the proximal joints of the lower pinnules often bear strong, thin, rounded _keels, or elongate pro- cesses,

and

thedistal joints

may

have overlapping

and

_spiny distal ends.

Color.

—

_Purple or yellow, or yellow or white,

more

or less heavily

banded

^ormottled with purple.

Geographic distribution.

—

_Tropical; Caribbean Sea at

Panama;

^east Africa eastwardtonorthern Australia

and

southern Japan.

Depth.

—

_Littoral, but occurring

down

to60 fathoms.

The

_short, stout _cirri, with short or squarish suhequal joints bearing dorsal spines ortubercles, andtheopposing spine ⁱⁿ the _center,

and

the round and _stiffened, hut otherwise not _specially differentiated, lower pinnules distinguish ^this genus ^at a glance.

The

included species are,

0. adeonse(Lamarck). 0.japonica (Hartlaub).

0. indent (Pell). 0.pinniformis ^(P.

H.

Carpenter).

0. caribbeaA. II. Clark. 0. serripinna ^{(P. II.} Carpenter).

0. carpenteri ⁽Pell).

Family

ANTEDONID.K.

Erythrometra

gen. nov.

Genotype.

—

_Antedon ruber A. II. Clark, 1907.

Radial laces low, about as broad as high; the dorsal surface of the radials is approximally vertical tothe dorso-ventral axis of the animal;

muscularFossae small, theirarea _scarcely greater than that of the inter- articular ligament ^{fossa', the} notch separating

them

_{broad, hut}compara- tivelyshallow, not reaching ^half

way

^{to the axial canal.} Centro-dorsal

Clark

— _{New Genera}

ofUnstalkedCrinolds.

127

hemispherical, the^cirrussockets irregular in distribution, but approach- ing ^fifteencolumnsof

two

each. Cirriwith about thirty joints, afew of theproximallongerthan _{broad, the} remainder _squarish, the distal not- bearing dorsal spines; the opposing spine ^is prominent, terminally ^situ- ated, reachingⁱⁿlength rather

more

than half the diameter of the pen- ultimate_joint; the spine^isalmost an isosceles triangle, arisingfrom the entiredorsal surface ofthe_joint

;terminalclawratherstout, wellcurved, rather longerthanthepenultimatejoint. Interradial areaswith

two

or threecolumnsofsmall,rounded interradial plates, notin contact;inter- brachial _plates

may

^or

may

^notbepresentbetweenthetwo

arms

of each pair^;disknaked. Costals rathernarrow,well separated, the^firstoblong, about twice as broad _{as long,} the second pentagonal, bothoccasionally furnished with small dentate _processes.

Ten arms

of comparatively elongate joints. First pinnule longer

and

stiffer than those following, butshorterthanthe^distal; thepinnule^ofthe fourth (epizygal) brachial

isabsent.

Color.

— _Salmon

_red,the pinnules thesame, or yellow; ^cirri white.

Geographicdistribution.

—

_Only

_known

from southernJapan, from the

Korean

Straits to

Sagami

Bay.

Depth.—

^{50to 100fathoms.}

The

_presence of interradial

and

interbrachial _plates on an otherwise

naked

disk, distinguish ^thisgenus^atonce fromall othergeneraof Ante- donidse; theabsenceof the first inner pinnule shoidd ^{be noticed.}

The

onlyspecies atpresent

known

is,

Erythrometra ^{ruber (A.}

H.

Clark).

Thaumatometra

gen.

now

Genotype.

—

_AntedonciliataA. II. Clark, 1907

(—

Antedon tenuisA.

H.

Clark,1907).

Radialfacetsaboutasbroad ashigh, the muscularfossa?large

and

well rounded,distallyseparated by^a narrow, sharp ^notch, which extendsfor lessthanone-quarter^of the length ^{of their} apposed sides; interarticular foss;e remarkably small, the ridge separating

them

from the muscular

fossa? horizontal in its outer _half, gently oblique ^{in its} inner. Centro- dorsal conical or sub-conical, the sides convex,

somewhat

_thickly,

and

almost _entirely, covered with crowded cirrus sockets. Cirri slender, numerous, ^{with fifteen}to thirty subequaljoints, allof whichare usually longerthan broad; ^there

may

^{be a}slight ventral overlap, but_{spines are} not developed^; theopposingspine ^isprominent, terminallysituated,

and

directly obliquely forward. Radials almost, or entirely, hidden

by

^the centro-dorsal ; costals moderately short, the costal axillary pentagonal,

more

orlessproducedposteriorly.

Ten

arms, the lowest brachials oblong, broader than _long, then triangular about as long as, or rather longer than, broad,distally

becoming much

elongate, quadrate, oralmost_oblong, with swollen articulations.

The

_calyx

and

brachials are often

more

or lessspinous.

The

firstpinnule^isslender,

composed

^of elongatedjoints,

and may

be somewhat, ^ornotatall, longerthanthesecond; thesecond

128

Clark

— _{New Genera}

_{of Vnstalked Crinoids.}

pinnule and those following ^{are stouter} than the _first,

and

_{bear long} fusiform_genital "lands.

Color.

—

_{Yellow orbrownish yellow.}

Geographic distribution.

—

_{Antarctic Seas, and Pacific Ocean north to}

Panama,

northern Japan, ^{the Sea of}Japan, and^theGulfofTartary.

Depth.—

¹⁴⁰to 1,600 fathoms.

The

_{elongate joints} of the first pinnule,

and

the occurrence of a genital gland on the second

and

of an _oblique opposing spine

on

the penultimate joint of the cirri distinguish this genus ^{at once} from all others.

The

species are almost all small, reaching the

maximum

size, in

common

with Psathyrometra

and

Heliometra, ⁱⁿ thenorthern _{part of}the Sea ofJapan.

The

species referable ^to thisgenus ^are,

T. abyssorum ^(P.

H.

Carpenter). ^{T. isis} (A. H. Clark).

T. alternata _(P. II. Carpenter). ^{T. Isevis} (P. II. Carpenter).

T. comaster (A. II. Clark). T. longipinna(P.

H.

Carpenter).

T. exigua^{(P. II.} Carpenter). ^T. parva ^A.

H.

Clark.

T. hirsuta _(P.

H.

Carpenter). ^T.parvula ⁽Hartlaub).

T. remota_(P. H.Carpenter).

Coccometra

_gen. nov.

Genotype.

—

_Comatula

hagenii Pourtales, 1869.

Radialfacets with long, narrow, triangular muscular fossa', separated from theinterarticular ligament^fossa' by^a strongly diagonal ridge;the radial faceis considerably longerthan _broad, and almost wedge-shaped

in outline. Centro-dorsal low-hemispherical, ^a rather _large area at the polehareand _{papillose. Thirty}to_fiftycirri with fifteentotwentyjoints,

proximally two ^{or three times as} long ^as broad, gradually

becoming

shorter_distally,the terminalfew _{not beinggreatly} longer than broad; no dorsal spines; opposing spine ^obsolete. Radials not projecting beyond the centro-dorsal; ^lirst costals very ^short, almost hidden in the

median

line by ^a posterior extension of the costal axillaries; there is a strong constriction at the intercostal articulation; costal axillaries longer than wide, the anteriorangle produced, and all thesidesincurved.

Ten arms

of moderately elongate joints.

Lower

_{pinnules long,} approximately equal ⁱⁿ length, the lirst

composed

^{of very}

numerous

short _joints, very delicate and _flexible, thesecond and following with about half as

many

joints, the proximal ^{three short, the} remainder becoming rapidly ^elon- gated; the second and _{following pinnules} hear _{large genital} glands.

After the secondand third the pinnules gradually decreaseⁱⁿlength, then

become more

^slenderand increaseagain, but do not reach the length of the ^lirstfour.

Color.

—

_{Pale greenish, turning} white in alcohol; or yellow, with a median _{stripe of black, or}with _largeround _spotsof

Mack

at the _syzygia.

Geographic distribution.

—

_{Caribbean Sea,} north to Florida.

Depth.—

^{82 to242fathoms} (Carpenter).

From

the genus Thysanomelra, which ^{also has the lirst} pinnule ^coin- posed ^of

numerous

short joints, and thesecond and_followingofelongated joints, Coccometra

may

^{be most} readily differentiated by the character^of

Clark

— _{New Genera}

_of UnstalJcealCrinoids.

129

the radial faces. In Thysanometra ^{these are} approximately oblong, broader than_long,themuscularfossa;large,transverselyronnded-oblong, separatedfrom theinterarticularligament^fossa?

by

^horizontalridges, the exteriorendsofwhichare

more

orlesscurved

downward.

InCoccometra,

asdescribed, these are wedge-shaped, elongate, themuscularfossaeelon- gate triangular, separated from the interarticular ligament ^fossae

by

strongly diagonal

and

straight ridges. Externally, Coccometra

may

^be

distinguished

by

^its longer

arm

_{joints, longer pinnule joints,}

and

short distalpinnuleswhicharenotsolong^asthe proximal, ^whilein Thysano- metra they are considerablylonger. Thisisthe onlycomatnlid genus ⁱⁿ which the coloration appears ^to have a systematic ^{value. It} includes three_species, one

which was

described

by

Pourtales, another mentioned

by

^Dr.

Hubert Lyman

Clark,

and

a third_{as yet}undescribed.

They

are,

C. hagenii (Pourtales).

('. nigrolineata

[=Antedon

hagenii

H.

L. Clark (not Comatula hagenii Pourtales⁾, 1901]^.

Leptometra

gen.

now

Genotype.

—

Alecto

phalangium

^{J. Muller, 1841.}

Radial faces wedge-shaped, very long, nearly, or _quite, twice as long asbroad, themuscular fossa'

much

elongated,

and

sub-triangular, separ- ated

by

a diagonal ridge from the fossae lodging the interarticular liga- ments,

and

in close opposition interiorly. Centro-dorsal hemispherical, conical, or

somewhat

columnar, _bearing from twenty ^to thirty cirrus socketswhich

may,

^or

may

not, be regularly arranged, but are always separated

more

orless from eachother. Cirri very long

and

_slender, of

more

than_fortycylindrical joints, slightly

more

_elongateproximally than distally, squarish, or longer than broad;

no

dorsal spines; usually

no

opposing spine. Radials

more

or less hidden; first costal short, second _usually pentagonal, rather _large, deeply incising the _first; the costals are strongly convex _dorsally,

and may

^or

may

^{not bein lateral}

apposition

and

_laterally flattened.

Ten

_long

and

slender

arms

of obliquelyquadrate or triangular joints, as long ^asor longer than wide.

Firsttwopinnules elongate, slender

and

flagellate, the first six or eight joints short, theremainder_elongate; following pinnulesshorter, but the length ^of the basaljointsgraduallyincreases, except thetwofirst,

which become somewhat

flattened; ovaries long

and

fusiform.

('olor.

—

_Green.

Geographicdistribution.

—

Mediterranean _Sea, west _{of Italy}

and

Tunis;

eastern _Atlantic, from theMadeira Islands northward_{along the}coasts of Europe,

and

westcoast ofthe BritishIslesto theHebrides.*

Depth.—

^45to189 fathoms.

The

_greatlengthof the muscularfossain thisgenus which ^are not ^in- teriorlyseparated by^anotchissufficient todistinguish ^itatonce. Exter- nallythe elongate

and

slender_cirri,

which

are

smooth

_{with very}

numerous

*Reportedalsofrom Hope,or Seahorse,Island, just southeastofSpitzbergeu; but Grieg has alreadycalled attentiontothefactthat thisisprobablya easeofmisidentifi- eation.

130

Clark

— _{New Genera}

_{of Unstalked Crinoids.}

joints,

and

the equality^ofthetwo proximal pinnulesreadily differentiate

it. Itappears^tobepossible todistinguish two_species, which are, L.celtica (Barrettand

McAndrew).

^L.

phalangium

^{(J. Miiller).}

Hathrometra

yen.

now

Genotype.

—

Alectro dentata Say, 1825.

Radialfaceswedge-shaped,^lessthan once and one-halfaslong^asbroad;

muscularfossaetriangular, ^lessthantwiceaslong^asbroad, not separated

)>y a notch; the ridge betweenthe muscular

and

interarticularligament fossaeisstrongly oblique. Centro-dorsalconical,thesides

somewhat

con- vex, thickly covered with small

and numerous

cirrus sockets, which are closelycrowded_together,

and

_arranged in

more

or less definite vertical rows. Cirri slender,with fifteen to forty-five joints,dimorphic,^theapical cirri having fewer _joints than the peripheral,

and

_being considerably smaller; the proximal cirrus jointsare

much

_longer thanthe_distal,

and more

orless "

dice-boxshaped"

; thedistalare squarish, or rather longer than _broad,and the dorsal ends

may

overlap^{so as to}producespines; an opposingspine^isalwayspresent,terminally^situated. Radials almost, or quite, concealed; ^{costal axillaries} rhombic, almost concealing the ^flrsl costals, which are_{short, in}the

median

_line; thecostalsarc roundeddor- sally,andin lateral opposition,though ^notlaterally flattened.

Ten

_arms, with triangular joints proximally,

becoming more

quadrate distally, always (exceptⁱⁿthefirstfewdiscoidal joints) aslongas,or longer than, wide. Firstpinnule long

and

_slender,twice or threetimesaslong^asthe second; the following pinnules gradually increase ⁱⁿ length; the _genital glands are long

and

fusiform.

Color.

— _Dark

green, or grayish green, sometimesdotted with white.

Geographic distribution.

—

_{Coasts of}

_New

Jersey and _Portugal north-

ward

to the ArcticOcean, and from ^{theseaswest of}Greenland eastward totheBarents and

Kara

Seas.

Depth.

—

25 orlessto

more

than600 fathoms.

The

characteristic conical centro-dorsal with its

numerous

crowded cirrus sockets, the great length ^ofthe firstpinnule and the absence ^ofa notch between the distal ends ofthe muscular fos.se, these being

much

broader than ⁱⁿ Leptometra, ^at once distinguish ^this genus. Hathro- metra contains the followingspecies:

IT.dentata (Say).

H.

sarsii ⁽

Dubenand

Koren).

//. prolixa (Sladen). ^{//. tenella} (Retzius).

Iridometra _{gen. nov.}

Genotype.

—

_Antedon adresline A. II.Clark, 1907.

Cirri fewand _short, with ten tosixteen_joints, the proximal elongate, thedistal shorter,onadiscoidal or low-hemispherical centro-dorsal.

Ten

arms, thejoints triangular, aboutas lout: as wide, becomingelongate^dis- tally. Firstpinnuleshort,never exceeding,andusually shorter than, the -croud, which doesnot beara_{genitalgland.}

Color.

—

_Varied and _bright, and _usuallymottled orbanded; ^brick red, white with purplebands, yellow-brown

banded

withdarker, purple and white, orpinkish.

Clark

— _{New Genera}

_{of UnstalkedCrinoids.}

₁₃₁

Geographic distribution.

— _Tonga

Islands

and

northern Australia to

Japan and

^the

Hawaiian

Islands.

Depth.

—

_Mainly

littoral, but extending

downward

to 150fathoms.

The

short

and weak

cirri with comparatively ^lew joints,

and

the small iirst pinnule are ^{sufficient to} differentiate thisgenus ^{at once.}

The

in- eludedspecies are,

/. adrestine (A.

H.

Clark). I. minuta (A. II. Clark).

J. briseis (A.

H.

Clark). I.

nana

(Hartlaub).

7".crispa A.

H.

Clark. I.parricirra (P.

H.

Carpenter).

/. psyche^(A.

H.

Clark).

Compsometra

gen.

now

Genotype.

—

AntedonloveniBell, 1882

(=

Antedon

pumila

^Bell,1884).

SimilartoIridometra,butthefirstpinnule^is

much

longer than, usually about twice aslong as, the second

and

_following,

and

the _joints of the proximalpinnules^all overlapstrongly.

Color(inspirits).

—

_{Olive grayor}brownish, sometimes

banded

_narrowly with darker.

Geographic distribution.

—

_{Port Jackson,}

_New

South Wales, northward to

Tokyo

Bay, Japan.

Depth.

—

_Littoral,and

down

to 12 fathoms.

The

extraordinary projection ^of the distal edges ^ofthe pinnule joints

and

^thesmallcirriwith comparatively fewjoints,whichare_distally

much

compressed

and

comparativelybroad, distinguishthis species atonce.

The two

_{species atpresent}

know

_are,

('. loveni (Bell). <?. serrata (A. II. Clark).

Trichometra

gen. nov.

Genotype.

—

_{Antedqnaspera A.} II. Clark, 1908.

Radial faces low, wedge-shaped, ^or almost triangular, the muscular

fossa-practically equilateral right-angle triangles, thedistal apices sepa- rated by a small, narrow, andacute notch ; ridgesseparating the

muscu-

lar

and

interarticular ligament ^fossa' horizontal. Centro-dorsal sub- conical, with

somewhat

_strongly convex sides, thickly covered with small cirrus sockets,

somewhat

crowded, roughly arranged ⁱⁿ two or threecolumnsineachradial area. Fortyto sixty ^cirri with twenty-five to thirty-five joints,elongateⁱⁿtheproximal^{half of the} cirrus, squarish inthe_distal, the_{joints in} thelatterhaving a sharply carinate dorsal^sur- facewhich_projects

more

orlessdistally,giving aslightlyspinousappear- ance; theopposingspine^isprominent, terminally situated, arisingfrom theentiredorsal surfaceofthe_joint, but does not reach the diameterof the_{joint in}length^; theterminal claw is rather longer thanthe penulti-

mate

_{joint, moderatelystout,}hutcomparativelyslightlycurved. "

Small mature

"

cirrioccuraboutthe dorsal_pole,

which

aresometimeslessthan halfthe length^oftheother_cirri, consisting^of ten ortwelve very slender

and much

_elongatedjoints,with _greatly

expanded

articulations. Distal edges^ofradialseven withtheedge^ofthe centro-dorsal,not extending

up

intothe angles ^of the centro-dorsal; first costals very short, sometimes

132

Clark

— _{New Genera}

_{ofUnstalkedCrinoids.}

sixor eight times^asbroadas long^{; costal axillaries}rhombic, ^asbroad as or broader than _Long; the costals are in close apposition,

and may

^he

laterally flattened.

Ten

_{arms, the joints (except} the proximal, which are transversely oblong ^or squarish), triangular or obliquely quadrate, aboutaslong^as wide,

becoming more

elongate distally.

The

first pin- nuleis exceedinglyslender, halfagain ^as long ^to three times as long ^as the stoutersecond _pinnule,

composed

^of

much

_elongatedjoints, especially distallywherethey are slender

and

threadlike, withthedistalends

much

expanded.

Color.

—

_Yellow.

Geographic distribution.

— Bahama

Islands to Savannah, Georgia ^;

Hawaiian

_Islands, aboutMolokai

and

thesouthern _partofOahu,

and

oft'

Maui.

Depth.—

^{270to440fathoms.}

The

_{peculiar, long} and slender first pinnule

and

the short _costals, together with the

numerous

cirrus joints wdiich are short _distally, the short opposing

and

long terminal spine, the latter but little curved, ^at oncedistinguish^this genus.

The

_only

known

species are,

T. aspera (A.^II. Clark). T. vexator (A. II. Clark).

Bathymetra

gen. nov.

Geiiott/pe.

—

_Antedon

abyssicola^P.

H.

_Carpenter, 1S88.

Centro-dorsal small, hemispherical, the^cirrussockets rather small

and

well separated, arranged

more

orless regularly^{in fifteen}columns, one^to threeto acolumn. Fifteento forty-five^cirri witheightto fifteen joints;

firstjoint short, secondlongerthanbroad, usually considerably elongated, the followingjointsgradually decreasingⁱⁿlength distally; ^all the _joints have_enlarged and Haring^distalends; ^{there are}

no

dorsal _spines, butthe opposingspine^isalways^welldeveloped,triangular,itsdistaledgevertical, its proximal edge straight, running from the anterior end ofthe penul- timate _joint to the _tip of the _spine. Radials always visible, usually^for a largepart^{of their} length, strongly concave on their anterior border, stronglyproduced ^{in the}interradialangleswhere_{theypartially}or_entirely separate the^first costals; costals

and

lower brachials in close apposition laterally,

and more

orless flattened; thecostals

and

the joints oftheten

arms

are all rather _long, the latter with a concave _surface,

making

^the ends prominent. ^Tin-lower pinnulesappear^{to be slender, with thefirst} shorterthanthe second.

Color.

—

Light grayish brown.

Geographic distribution.

—

Bering Seasouthward tothe AntarcticOcean, northin the AtlantictotheAbrolhos Islands, oil'the coast of brazil.

Depth.—

^{818 to}2,900 fathoms.

The

_elongationof thesecond cirrus joint and the interradial processes ofthe radialsdistinguish ^thisgenus^atonce fromallothers.

The

included species are,

B. _abgssicola (I*. II. Carpenter). ^II. carpenteri ^{A. II.} Clark.

//.brevicirra A.

H.

Clark. /.'. minutixxima A. II. Clark.

ClarL

— _{New Genera}

_{of Unstalked Crinoids.}

₁₃₃

Hypalometra

gen. nov.

Genotype.

—

Antedon_{dejecta P.}

H.

_Carpenter, 1888.

Radial faces longer than _{broad, the} muscular fossa? large, the notch between

them

broad, but very shallow. Centro-dorsal hemispherical, or

more

orlesssub-conical, thickly covered with cirri, a small polar area bare. Cirri twentyto thirty, with twenty ^to twenty-five joints, one or

two

of the basal about three times as long ^as wide, thence _decreasing distally, the_{joints in}theterminalhalf being squarish; no dorsal spines;

opposing spine well developed. Eadials visible, not extending

much

beyond ^the edge ^{of the} centro-dorsal; costals moderately long, well rounded,

and

_{widelyseparatedlaterally.}

Ten arms

ofrather longjoints.

First exterior

and

firstinteriorpinnule absent; the lowest pinnule^isthat of the fifth brachial, which ^is borne on the outside of the

arm;

^{it is}

composed

^of(except the basal) elongatejoints,

and

bears a_genitalgland;

the following\innules decreasein length,thenincrease again distally.

Color (in spirits).

—

_{White, the}

_arms

_{sometimes crossed with}

_narrow

transverse

brown

bands.

Geogra)dii<-distribution.—Caribbean _Sea, northtoFlorida.

Depth.—

^{77 to242fathoms} (Carpenter).

The

hemispherical centro-dorsalbearing

numerous

cirri which have a moderate

number

_{of joints,} elongate proximally, squarish distally,

com-

bined withthe entireabsence of oral pinnules (the lowest pinnule bear- ing agenitalgland) distinguish ^this genus ^atonce from all others.

The

only

known

_species^isthe

common

Hypalometra defecta (P.

H.

Carpenter).

Isometra

gen. nov.

Genotype.

—

_Antedon lineata P.

H.

_Carpenter, 1888.

Centro-dorsal hemispherical or sub-conical, almost _completely covered withcirrus sockets. Cirriabouttwenty-fiveⁱⁿ

number

withabout _thirty joints, subequal, approximatelysquarish, overlappingdorsally, thedistal sometimes with

more

orless developed spines. Radials about even with theedge^ofthe centro-dorsal; firstcostalsoblong, abouttwiceasbroadas long; costal axillaries pentagonal, wider than _long; the costals are rounded

and

_{entirely separated} from each other.

Ten smooth

_arms;

brachials at first oblong ^or slightly wedge-shaped, broader than _long, then

becoming more

obliquely wedge-shaped

and

as long#as, or longer than, wide,

becoming

elongate distally. First

two

^or three pinnules slender, "styliform," with _{elongate joints; following (genital)pinnules} with the third

and

fourth _joints

expanded and

broadly V-shaped.

Geographic distribution.

—

Only

known

from the south _Atlantic, off Uruguay.

Depth.—

600 fathoms.

This genus ^is readily distinguishable from all the other genera ^of Antedonidae by ^the

expanded

joints of the _genital pinnules.

The

_only

known

species is,

Isometra angustipinna (P.

H.

Carpenter).

134

Clark

— _{New Genera}

_{ofUnstalkedCrinoids.}

Isometra angustipinna ^is withoutdoubtthe

young

^{of Antedon lineata} P.

H.

_Carpenter, 1888 (not Antedon lineatus Pomel, 1887), which

was renamed

challengeri by ^{A. II.} Clark in 1907, before its relation to angustipinna wasdetected.

Family PEXTAMETROCRIXID.E nom.

nov.

Pentametrocrinus

gen. nov. ^.

Eudiocrinus ^P.

H.

Carpenter, 1882 (part), but not Ophiocrinus Semper, 1868 (not OphiocrinusSalter, 1856).

Genotype.

—

Eudiocrinus japonicus^P.

H.

_Carpenter,1882.

Costals absent, the ^first post-radial joint being the first brachial; no orals; ^rivearms.

Color.

—

Purplish gray, the disk black.

Geographicdistribution.

—

Intertropical;

West

_Indies; coasts of south- ern Europe; ^{coast of}Somaliland eastward through ^theIndian

Ocean

to southern Australia, northward toJapan.

Depth.

—

103to 1,050fathoms; mainlyabyssal.

Eudiocrinus wasoriginally differentiated from ^"

Antedon"

on account of the possession ^{of five} undivided arms;

and

itseems to have_escaped the notice^ofall subsequent workers on ^thecomatulids that theundivided

arms

of theEudiocrinus indivisustype areradically different instructure fromthoseoftheEudiocrinus japonicus type. Eudiocrinusindivisus,E.

granuiatus,

and

E. _variegatus (thefirst the type ^ofthe genus) have

two

costals united bysyzygy, ^{as in} Zygometra, ^thegenus ^to which_they

show

the closest affinity; but they ^differ from Zygometra ^{in that the} second costal bearsapinnule instead^of anadditionalarm.

The

third post-radial joint ^is the real first brachial, and is joined ^to the succeedingjoint

by

synarthry, ^as the first brachial isjoined ^tothesecond inall comatulids;

there is, of course, no _pinnule

on

this joint, as the first brachial never bears a pinnule; the fourth post-radial joint {i.e., second _brachial) is

joined ^to the succeeding by an "oblique

muscular"

articulation, asare all second brachials tosucceeding joints; ^it bears a pinnule on ^theside opposite^{to that}onwhich thecostal pinnule^isborne,^{as a}synarthrial^arti- culation, like^itsderivative, a syzygy, notonly neveradmits ofthe devel-

opment

^{of a} pinnule, hut ^is non-effective in regard tothe pinnule^devel- oped on^the next obliquemuscular articulation, which,therefore, occurs onthe

same

side as itwouldifthe synarthry or syzygywerenot_there,but the two _joints were merely ^a single joint.

A

muscular articulation,

on

the otherhand, always ^{affects the}position ofthenext pinnule, no matter whether ^a pinnule ^is developed ^{at the} articulation or not, causing ^itto appear on ^the

same

side astin' precedingpinnule^; Perometra

and

_Cyllo- metra andalso Erythrometra ^areexamples ^ofthis, between the fifth and sixth post-radial joints ^(i. e., thethird and fourth brachials)occurs the

first syzygy, which, ^therefore, occupies the

same

position as in Zygometra

and

in almost all other comatulids. In "Eudiocrinus"

atlanticus,

E.

japonicus, E. _semperi, E. tuberculatum, and 7*-'. varians, as ⁱⁿ Decametro-

Clark

— _{New Genera}

ofUnstalkedCrinoids.

135

crinus

and

Thaumatrocrinus, the costals* are absent,

and

the firstpost- radial joint ^isthe first brachial.

As

an item of considerable interest it

may

^{bementioned thatinthese}species of

"

Eudiocrinus,"

inDecametro- crinus, Thatnnatocrinus,

and

Uintacrinus, the ^firstsyzygy^isbetween the fourth

and

fifthbrachials, not between the third and fourth as is

com- monly

^thecase; inanalyzing the

arms

of Uintacrinus*^itmust be

remem-

bered that there are two distichals present, of which the second is not an axillary, so that the first brachial is the third _joint from the costal axillary.

The

_genus Pentametrocrinus, ^as here defined, contains the following species^:

P. atlanticus _(Perrier). P. semperi (P.

H.

Carpenter).

P.japonicus (P.

H.

Carpenter). P. tuberculuttts (A.

H.

Clark).

P. varians _(P.

H.

Carpenter).

Some

_{time ago} I proposed the family Eudiqprinidse ^to cover these species

and

Decametrocrinus, not being aware ^{at the} time that Eudio- crin us indivisus

was

so radically different. Eudiocrinus ashererestricted belongs ^to the family Zygometridae ^{with the} genus Zygometra, ^while Pentametrocrinus

and

Decametrocrinus

may

^{be united under} the family

name

of Pentametrocrinidas, which is the exact equivalent ^to

what

I intended

by my ^"

Eudiocrinidse.

"

_Minckert's

family

"Decametro-

crinidse"

must

be _rejected, it being

composed

^of Promachocrinus, a genus ^of Antedonidse _very near Heliometra, and the _utterly different Decametrocrinus.

The arm

structureof Thaumatoerinussuggests thatin reality^itbelongs to the Pentametrocrinidse, near Pentametrocrinus.

The

_generaof freecrinoidsbelonging^totheComatulida

may

^begrouped as follows, the

most

specializedtypesbeingplaced^first.

Family UJNTACRINID.E.

Uintacrinus.

Family COMASTERID.E.

Comatula. Co-master. _,

Family ZYG< (METRIDJv

Eudiocrinus. Zygometra.

Family HIMEROMETRID.E.

Himerometra. Cyllometra.

Pontiometra. Oligometra.

Family TROPIOMETRID^E.

Tropiometra. Calometra.

Asterometra. Ptilometra.

*Thecostals are, in reality,merelyrepetitions of the twofirstbrachials ofthe free

arminterpolatedbetweentheregularfirstbrachialsandthe radials; the distichalsand palmars ^areadditional reduplicationsofthetwo firstbrachials, either single (2) or double(4[3

+

^4]or4[1

+

^{2; 3}

+

4]),thetwopairs in this latter casebeing separatedby a musculararticulationlikethat at the distalendofallcostalanddivisionseries.

136

Clark

— _{New Genera}

ofUnstalkedQrinoids.

Family THALASSOMETRIDjE.

Paecilometra. Thalassometra.

Charitometra.

Family ANTEDONIDjE

(restricted).

Pirometra. Leptometra.

Eryihromelra^. Hathrometra.

Zenorrwtra. Iridorrutra.

Psathyroim^tra. Trichometra.

Adeloinetra. Bathymetra.

Heliometra. Nanometra.

Promachocrinus. Compsometra.

Thaumatometra. Hypalometra.

Thysanometra. ^Isometra.

Coccometra. Antedon.

Family PENTAMETR< >CRINID^E.

Decametrocrinus. Pentametrocrinus.

Thaamatocrinus.