234 SMITHSONIAN MISCELLANEOUS COLLECTIONS [VOL. 47 Basal pectinirhomb in the specimen of average size above men-

234 SMITHSONIAN MISCELLANEOUS COLLECTIONS

^[VOL. 47

SCHUCH1 ^I| SILURIC

AND ^DEVONIC

^{CYSTIDEA 235} Pectinirhombs on ^{plates 1}

and

5, 12

and

18, about equally large and having about 33 dichopores, while that on plates 14

and

15 ^is largest and has _43.

Madreporite prominent, ^{situated as usual} on plate 18; the hydro- pore is very minute.

Anal area as in P. clarki, prominent, consisting of 2 circles of pieces, diemiter one

made up

of 4 or ₅ right posteriorplates, ₃ minute pieces on the left, and plate 13.

The

^inner

pyramid

^{is not preserved}

in the specimen at hand.

Comparisons.

—

^{This species is}

^most

closely related toP. elongatus, but the greater size and elongated theca of the ^{latter will readily dis-} tinguish it. P. clarki is similar, hut the greater size, oval outline,

and

^the differently sculptured plates will serve to identify ^it.

Formation and

^locality.

— ^The

^{only specimen}

^{known was}

^{found by}

Mr.

Hartley at Devil's Backbone, opposite Corringansville, near

Cumberland,

^Maryland.

The

horizon is in the upper portion of the

Manlius

or thelower half ofzone "D. ^P>. Ba." of the section described by the writer on p. 418, Proceedings of the U. S. National

Museum,

1903.

Cat.

number

35,067,

U.

S. N.

M.

Presented by Mr. Robert

H.

Gordon.

PSEUDOCRINITES ELONGATUS

n. sp.

(Plate

XXXV,

figures 6, 7)

Oral end of the only specimen broken away, but the length seems to

have

been about 40

mm.;

^width 23

mm.;

^depth 17

mm. ^For

general

form and

^shape of individual ^{plates, see} figures 6, 7, plate

xxxv, and

text-fignre 31.

Ambulacra

prominent, extending

around

the entire periphery of the theca

and

touchingthe column.

As

the top of the theca is broken

away,

the exact

number

of

q~

brachioles cannot be counted,

__

f^Z^y,^

but. on the basis of brachioles preserved

and

the close rela- tionship to P. siibqiiadratus, the total

number

on each side ofan

ambulacrum

is estimated to be

between

26

and

28.

Am-

bnlacralgroovelarge

and

deep;

ambulacralia not preserved.

Basal pectinirhomb has about 65 dichopores. that of plates 12 and 18 about 75,

and

of plates 14

and

15 about

no.

0£W,

Fk

31.

—

^{Analysis of} Pscudocrinites elongatus n. sp.

236 SMITHSONIAN MISCELLANEOUS COLLECTIONS

^[vol. 47 Comparisons.

— As

the various forms of Pseudocrinites are easily recognized on account ^{of their} constant characters, the writer does not hesitate to describe this broken specimen as a

new

^species. Its greatly elongate,

narrow form

distinguishes it

from

all the others.

P. clongatiis is closely related to P. subquadratics, as both

have

the

same

general form, size of ambulacral plates,

and

sculpture, but the formeris readily separated

by

being

more

elongate with the sides of the theca straighter,

and more

especially by the far greatersize, being 2^2 times larger than P. sitbquadrattts.

Formation and

locality.

— ^The

^holotype

^{was found}

^{by Air.}

^Perdew

in the Manlius formation on Martin's mountain, near

Lodger

Per-

dew

^'s

farm

ⁱⁿ Pleasant ^valley,

Bedford

county, Pennsylvania.

Cat.

number

35,065,

U.

S. X.

M.

PSEUDOCRINITES PERDEWI

Schuchert

(Plate

XXXVI,

figures 1-3; Plate

XXXIX,

figures 8-10) Pseudocrinites perdewi Schuchert, Amer. Geol., xxxn, 1903, p. 238.

The

four following specimens represent four stages in the

growth

of this species

Length|Width Depth Brachioles(total) Rhomb1-5 Rhomb12-18 Rhomb14-15 Specimen i 16

mm

1 1

mm

Specimen2 24 " 17

9

mm

Specimen3 Specimen4

27 39

15

?20

23 48 76 90

\20dichop.

42 "

53 "

82 "

34^dichop.

48 "

65 ^<<

114 "

40dichop.

58 « 82 "

General

form

pear-shaped, with the sides appressed.

of the individual

CV)

/T/6B

For

shape plates

and

their ornamentation, see the

diagram and

plate-figures.

Ambulacra

wide,very

prom-

inent, with vertical angulated sides

and

^{flat or} slightly trough-shaped oral surfaces.

In specimen

number

i, the 2 ambulacra taper rapidly

and

extend along the periphery of the theca for one-third its

length. In

number

2, theyare just one-half the length of the theca, in

number

₃ nearly two-thirds the length, while in

number

₄ they are about one-half the length.

This

shows

that the length of

mature

ambulacra is

somewhat

vari- 32.

—

^{Analysis of} Pseudocrinites

perdewi Schuchert.

schuchert] siluric

and devonic

cystidea

237

able extending from ^one-half to two-thirds the thecal length.

The ambulacrum

nearest the anal region is always

somewhat

shorter.

Number

of brachioles

on

one side of each

ambulacrum

varying with age, there ^being- in the youngest

known

specimen ¹no. 1 ) about 5. in a

mature

individual (no. 3 ⁾ about [9,

and

in the largest

example

^{( no.}

4) about 22.

Ambulacral

grooves

narrow

ⁱⁿ comparison with the large size of the ambulacrals, and covered by very small rectangular ambulacralia

which

^arc sharply elevated into a

median

ridge.

There

are usually from 10 to [2 ambulacralia to each ambulacral, but in different specimens the

number

varies.

The

branches

going

to the brachioles at the lateral ends of the plates have the ambulacralia as well developed as the

median

series. Brachioles slender,

composed

of rather large, elongate,

smooth

pieces.

Those

at the distal ends of the ambulacra have 6 pieces in a

column

4

mm.

long; seemingly these brachioles did not exceed 12

mm.

in length.

Anal

area small, not prominent,

and composed

of 2 circles of plates.

The

outer circle has

from

7 to 9 ^{pieces of} unequal size,

and

the ilat

pyramid

has 7 or 8 equal triangular ^pieces.

The

madreporite is rather large for Pseudocrinites, but the hydro- poreisminute,

and

bothare placed within a distincthollow separating the ambulacra of one side.

Basal pectinirhombsmallest, that of plates 14

and

15 largest.

Column

slender, tapering rapidly for a short distance

from

the theca,

and composed

of pieces of equal thickness.

Length unknown.

Comparisons.

—

^{This splendid large}

^{and odd}

Pseudocrinites ^is readily distinguished

from

^all other species of the

genus by

theshort, high,

and

angulated ambulacra.

The form

of the theca

and

the plate sculpturing are also characteristic.

Formation and

locality.

— ^Of

^this

^form

^{the National}

^Museum

^has

five excellent examples, the Geological

Survey

of

Maryland

one,

Mr.

Gordon

one,

and

Air. Hartley twelve. All are

from

the cystid beds of the

Manlius

in the quarries near Keyser,

West

Virginia.

The

specific

name

^is given in recognition of the assistance rendered the writer by

Mr. George M. Perdew

^of

Cumberland, Maryland.

Cat.

number

35,072,

U.

S. N.

M.

Trimcrocystis n. gen.¹

Generic characters.

—

Staurocystinae having the general structure of Pseudocrinites, but differing ⁱⁿ having ₃

ambulacra

instead of 2;

these are aslong as the theca,

and

are

R

^I,

R

IV,

and R

V.

Another

^he

^generic

^name

^{lias reference to the tripartite divisions of the ambu-}

lacra in this cystid.

23^ SMITHSONIAN MISCELLANEOUS COLLECTIONS

^[VOL. 47