Description of a new Cretaceous <I>Pinna</I> from New Mexico

PROCEEDINGS OF UNITED STATES NATIONAL MUSEUM. 47

Fig._1, on Plate ,represents one ofthe examples referredto, the principal portion oftliefigureshowinga naturalcast ofthe dorsalvalve, with the

nmbonal

portion of the ventralvalve. In this figure thefull length of the shellfromback to frontis not shown, butit is represented inthe acconiijanying diagram, Fig-. 2.

Washington,

D.

C,

December3, 1879.

NOTE OX ACKOTHEIiE.

By

C. A.

\%^HITE.

Among

thefossilscollectedfromPiimordialstrata atAntelopeSpring, Southern Utah,

by

Mr. G. K. Gilbert

and

Mr. E. E. Howell,

who

were then connectedw^ith the exi^lorations

and

surveys west of the 100th meridian,were a

number

of examples of adiscinoid brachiopod. This form Idescribed

and

figuied* under the

name

of Acrotretaf subsidua, referring ittothat genusprovisional!}'. JSToue of theexamples werein a conditionto

show

all the generic characters clearly, butcertain fea- tures in theseshells indicated their i^ossession of importantdifferences from

any

genus then established

and

led

me

to suggest that they prob- ablyrepresented a

new

generictype. Inthe

same

year, 187G, Prof. G.

Linnarsson, ofStockholm, Sweden, publishedt a

new

genericform from the Primordial rocks of Sweden, under the

name

ofAcrothele^ which plainlyincludes Acrotreta? subsiduaWhite. ProfessorLinnarssondes cribed

two Swedish

speciesunderthis generic

name

(A. coriacea

and

A.

granulata),

and

in 1870 he published a third species underthe

name

of A. intermedia,^but A. siibsidua is at present the only

known American

species. Itisnot unlikely,however,that

some

of the

American

^species heretofore referred to])isci)ia willbefound tobelong to Acrothele.

Washington,

D.

C,

February1, 1880.

DESCRIPTIOiV OF A NEW CKETACEOIS

PIIVIVA

FROm TiEW MEXICO.

By

C. A.

IVHITE.

Pinna stevensoni.

Shell large, elongate-triangular in marginal outline; valves moder- ately convex; the convexity being slight

and

nearly uniform poste- riorly,but

much

greatertoward the front,whereit

amounts

toan obtuse median angularity

upon

each valve,

and

wheie a transverse section of theshell has an approximatelyregular rhombic outline; upperborder

*Expl. ami^Siir.WestoftlielOOtli Merit!.,Vol.IV,p.34, pi.I, fig.3,a, b, c,audd.

tBihangtillk.Svenska Vet. Akad Handliugar,Baud3, No. 12, p. 20, pi.IV,figs.

44-52.

tSvcriges Geologiska Uudersokuiug; Ser. C. Afhaud. ock Upps. No. 35, p.25, pi.

iii, figs.40-44.

48 PEOCEEDINGS OF UNITED STATES NATIONAL MUSEUM.

straight ornearlyso; lowerborder slightlyconvex

and

longerthanthe nipperborder; posteriorborder nearlystraightorslightly convex,trun- cating the shellobliquely

downward and

backward, meetingtheupper borderata

more

orless distinct obtuse angle

and

thelower border

by

an abruptcurve. Surface

marked by abundant

coarselines

and

imbri- cationsofgrowth,whichtraversetheshell in slightlycurvedlinescorre- sponding with theposterior border,

and

is apparentlywithouttrace of

any

radiating lines orribs.

Entire length from beak to postero-basal extremityabout 215 milli- meters; breadth, from the postero-dorsal extremityto the base, meas- ured at rightangles with theupperborder,95millimeters.

This shellis sounlike

any

described

American

speciesthatnodetailed comparisonwith

any

of

them

is necessary; butitisso closely related toP. legeriensisd'Orbignj^,from thedepartmentof Sarthe, France, that

itisnotwithout

some

hesitation thatI have decidedtopropose asepa- ratespecific name. Ihave never

had

an opportunityto examine

any

of the few examples of P. legeriensis that have teen discovered,

and

my

comi:)arisons are therefore only with the description

and

figuresof d'Orbigny, in Pal. Frangaise, Yol.Ill, p. 257, pi. 334.

From

these it

appearsthatourshell differs fromP. legeriensisin the followingparticu- lars.

The

angle ofdivergenceofthe npi)er

and

lowermarginsisnot so great, inconsequence of which thebreadth of the shell is not propor- tionally sogreat; the curve

by

which the i)osterior border meetsthe lowerborderis

more

abrupt,

and

thegreatesttransversediameter ofthe shellis nearilie

median

lineinstead ofbeing

much

belowit,asitisrep- resented tobeinP. legeriensis.

The

internal

median

grooves

upon

each valve, and alsothe undulations ofthe lowerborder,mentioned

by

d'Or- bigny, appearto beentirely wantinginourshell.

Pjositionand locality.

—

^{Cretaceous strata; about li miles southwest-}

ward

from Fort

Win

gate, ISrorthern

New

Mexico,whereit

was

^collected

by

Mr.

James

Stevenson, in whose honorthe specific

name

is given.

WASHmaTON,

D.

C,

February15, 1880.

NOTE

OlS

THE OCCURRENCE OF STRICIttrANDINIA SAliTEKI AND

S. I>AYBI»»$ONS BN

CEORGIA.

By

C. A.

^WEflTE.

A

few

months

ago Lieut. A. Vv". Yogdes, United States

Army,

gave

me

afew fragmentary fossils froma collection which he

had

thenlately

made

at Taylor's Eidge, in the

town

of Ringgold, Catoosa County, Georgia.

The

other fossils of this collection

and

the geology of the regionreferred towere discussed

by

Lieutenant

Yogdes

in the

Decem-

ber, 1879,

number

of the

American

Journal of Science

and

_{Arts, pp.}

475-477.

He

there refers,

and

doubtless correctly, the horizon from which heobtained the fossils hegave

me

to that of the Clinton Groui^