Description of new species of shells chiefly from Magdalena Bay, Lower California

Vol. 31,pp. 5-8 February 27, 1918

PROCEEDINGS

OFTHE

BIOLOGICAL SOCIETY OF WASHINGTON

DESCRIPTION OF NEW SPECIES OF SHELLS CHIEFLY FROM MAGDALEN A _BAY, LOWER CALIFORNIA.

BY W. H. DALL.

In

the course of

a

revision of the

West American

collection in the

National Museum

the following species

appeared

^to

be undescribed

^:

? Scintilla chloris,

new

species.

Shell ofa pale green^color, translucent,with

more

orlessevident paler rays, the

umbo

darker than the rest of the disk; inequilateral, rather compressed, the posteriorend wider, longer,rounded; the anterior

end

shorter, attenuated; the exterior polished, with slight concentric irregu- larities of growth,

and

_{extremely faint,} partly obsolete ^radial striulse;

hingewith a longamphidetic ligament^infrontofwhichinthe leftvalve

is a _single noduliform _denticle,

and

behind which is a _feeblyindicated lateral lamella; the scar of the ligament ^is long

and

narrow, ^{there is}

no

evidentdivision into ligament

and

resilium

which

might perhaps be visible inaperfectly freshspecimen.

The

interior of the disk isso pol- ished that the muscular

and

pallial scars are not distinguishable, but underthe microscopea sparse punctationcan be

made

out; themargins areentire. Length of valve, 9.0; length^of the part in front^ofthever- ticalfrom the

umbo,

3.0; height, 6.0; double diameterof theleftvalve, 2.0

mm.

Habitat.

— _Magdalena

_Bay, L. Cal., collected by ^{C. R. Orcutt.} U. S.

Nat. Mus. Cat. No. 218179.

Two

^leftvalves wereobtained.

The

shell isnot absolutelyidentifiable with Scintilla as defined, but seemsnearest to that genus, ^{so until it is} possible todescribe the charactersofboth valvesitseems best to leaveit

with that genus.

Macron

orcutti,

new

_species.

Shell of moderate_size, solid, fleshcolored under a

brown

villous peri- ostracum, the aperture white, the throat pale purple; nucleus lost, re- maining whorls five, moderately rounded, ^{the suture distinct} but not

3—

Peoc.Biol. Soc.Wash.,Vol.31, 1918. (5)

6 Proceedings ^{of the} Biological Society of

Washington.

channelled; the generalform Buccinoid; the surfacefinely, sharply uni- formlyclosely spirally striated^; towardthe base there areaboutfoursharp distant stronger grooves, the posterior^largerthan therest

and

terminat- ing ^atthe outer lip in a shortspur ^or tooth; siphonal ^fasciole strong, twisted, keeled; aperture longerthan the _spire,obovate, with a strong subsutural calluscontinuedintothewhorlasaspiral ridge; inner lip

and

pillarwith a

smooth

arcuate coat^of white _callus; outer _lipwith about 15internal lira?; canalshort, deep, recurved. Length ^ofshell, 36; oflast whorl, 32; ofaperture

and

_canal, 26;

max.

_diameter, 21

mm.

Habitat.

— _Magdalena

_Bay, L. Cal.,C. R. Orcutt. U.S. Nat.Mus.Cat.

No. 218185.

It

was

a surprise ^{to find} a third _{species of}

Macron on

thecoast, espe- ciallyoneofsuchsize,

and

conspicuously ^distinct from

any

^ofthemuta-

tions of

M.

_aethiops.

Two

specimens were^obtained.

Phenacolepas magdalena, new

species.

Shellwhite with a yellowish periostracum, nearly orbicular; anterior slopelong,convexlyarched, posterior slopeshorter, straight^; apex minute, pointed; sculpture^offaint closeradiating threadsuniformlydisposed but not crenulating the

margin

^; these are crossed

by

lowconcentric sculp- ture cutting the threads into nodules; ^interiorwhite, the^lateralmuscular impressionsvery broad; length^ofshell, 15.5; apex ^{infront of}posterior edge, 3.5; breadth, 14.5; height, 5.0

mm.

Habitat.—Magdalena

Bay, L. Cal., C. R. Orcutt, U.S.Nat.

Mus.

Cat.

No. 217907.

Thisisthefirsttypical species ofthegenus^decribed from

West

America.

Crepidula^{osculans C. B.}

Adams,

from

Panama,

^afterward

named

Scu-

tellanavicelloidesbyCarpenter,^isthe only otherspecies ofthe family

on

recordfrom this coast,

and

asthatappears^to haveasort ofledge^inside the posterioredge

and

a terminal apex (hence^the"

Crepidula") ^itcan hardly belong^tothegrouptypifiedbyP. crenulatus Broderip.

Marginella ^californica Tomlin,

new

var. parallela.

ShellresemblingtheCalifornian raceofthe_speciesbut uniformly^smaller.

The

_typicalform hasafaintnarrow_spiral

brown band

atthesuture, then a paleband, then ^abroad yellow-brown band,^a narrower pale band, a second broad

brown band beyond

^{which theshell is}pale^tothe anterior end;

— _when

the shell is not unicolorate.

The

present variety has the broad

brown

bandsrepresented by narrow dark

brown

_paired^lineswith a faintflush of

brown

between them, giving the ^shell a very^different aspectfromthe _type.

Length^ofaveragecalifornica, 8.5; breadth, ^4.0

mm.

"

"

var. parallela, 6.7 " _3.0 "

Habitat.—Magdalena

Bay, L. Cal., C.R.Orcutt. U.S.Nat.Mus. Cat.

No. 217843.

Numerous

specimens were ^collected.

Doll

—

NeicSpecies of Shells

from Lower

California. 7

? Trichotropis

(Provanna) lomana, new

species.

Shell thin, whiteunderadull smooth olive-green periostracum, ^decol- late but _indicating

more

than threewhorls; suture deep but ^not chan- nelled, whorlswell rounded; axialsculpture on the lastwhorl of about twentyslightly arcuate _ribs, with subequal interspaces, ceasing abruptly at the periphery; on the precedingwhorls these extend from suture to suture; on thebase theaxialsculpture^isreduced toinconspicuous incre- mental lines; spiral sculpture, behind the periphery, ^ofobscureclose-set threads only^{visible in} the interspaces; ⁱⁿfrontofthe periphery

and

be- tweenit

and

the canal are four or five strong cordswith narrower deep interspaces, slightlycrenulating the thin anteriormargin ^{ofthe outer}lip;

aperture rounded, throat white, showing ^the impress ^of the external sculpture;

body and

^inner lip with a thin white _layerof callus; pillar arcuate, angulate ^at the extremity; canal very ^short

and

rather wide.

Length of (decollate)

two and

a halfwhorls, 7.0; of ^lastwhorl, 6.0; of aperture, 4.0;

max.

_diameter,5.5

mm.

Habitat.

—

OffPoint

Loma, San

DiegoCo., Cal., at station 4354, U. S.

Bureau

of Fisheries in650 fathoms,

mud,

^bottomtemperature, 38°5 F.

U. S.Nat. Mus. Cat. No.209112.

This_specieswants the fimbriateperiostracum ^ofTrichotropis

and

the canalis

more

rounded than in the shallow water _{species ofthe genus,} butintheabsence of softparts

and

_operculum theshell seems nearerto thatgroup than ^to

any

^other.

The

_typeofsculpture^recallsthatof

some

Rissoidaeand

some

_{species of} Chrysallida.

Liotia ratnmata,

new

species.

Shelldepressed-turbinate, ^of four whorls, the^firsttwo

and

two-thirds whorls

and

thebaseofthelastwhorlwhite, the upper^{surfaceofthelast} whorl and one-third reddish purple; the suture distinct,not appressed;

spiral sculpture on the _{spire of} two prominent threads, the posterior angulating the shoulder, the anterior growing

more

feeble on thelast

whorl; ^{the rest}of the surface isuniformly^coveredwith fineequal^close- set smaller threads _slightly roughened by ^fine incremental _lines; the only^axial sculpture consists of feeble

more

orless obsoleteplications in frontof the suture; base rounded, with a small perforate umbilicus of which the margin ^is notcrenate; aperture ^circular thickened below.

Breadthofshell, 4.7; height, 4.0

mm.

Habitat.—Magdalena

Bay, L. Cal., C. R. Orcutt. U. S. Nat.

Mus.

Cat.No. _217,908.

Liotia olivacea,

new

species.

Shell of five depressed-turbinate whorls, suture narrow but _{not ap-} pressed, the color verydark olivaceous, the prominentsculpture paler;

nucleusminute, decorticated, but_apparentlysmooth; spiralsculpture^of ontheupperpart^ofthelastwhorlfour strong elevated cordswithwider, almost channelled interspaces, the two posterior cords

more

_adjacent;

8 Proceedings ^ofthe Biological Society of

Washington.

on

the_spireonly three cords arevisible, the anterior

more

orless undu- lated;

on

the base are a _single cord, awide interval,then three

more

adjacent smaller plain ^cords,then three close-set beaded cords at the verge^of the small perforate umbilicus; aperturecircular, upper lippro- duced

on

the body, the ^interior pearly white; breadth of _shell, 6.2;

height, 5.5

mm.

Habitat.

— _Taboga

Island,

Bay

^of

Panama, James

^{Zetek. U. S. Nat.}

Mus. Cat. No. _331,837.

Another specimen, long ⁱⁿ the collectionfrom

Panama,

^{but with}

no

collector's name, has ^{all the} spiralsculpture strongly beaded,

and may

be calledvariety^{litharia. I} have no doubtit isan extreme _varietyof the

same

_species.

Liotia

(Arene)

cookeana,

new

species.

Shell small, white, depressed, with a

narrow

crenulated suture

and

three rapidly enlarging ^stellate whorls; ^axial sculpture ^of (on the last

whorl 13) prominent narrow ^ribs with wider interspaces, acutely pro- duced at the periphery,

and

_{extending nearly}to the crenate

margin

^of the funiculate umbilicus^; thewholesurface inaddition is covered with fine close-set sharp almostmicroscopic^axial threads ; beyond ^the peri- phery are four or five spiral cords

which

do not appear on ^{the ribs;}

aperture ^circular, the

margin

crenated

by

^the sculpture. Breadth of shell,3.0; height, ^1.0

mm.

Habitat.

—

In 7 to 10 fathoms off South

Coronado

Island, Dr. Fred Baker. U. S. Nat. Mus. Cat. No. _223,290.

This_species

may

attain a larger^sizebut

none

is

known

inthe California faunaof

which

^it _{might be} the young. ^{It is}

named

inhonor of Miss J.

M. Cooke

of Point

Loma,

Cal., to

whom we

are indebted for

many

interesting^shells.

Liotia acuticostata,

new

var. radiata.

Shell resembling the typebut with

numerous

_radiatingribletsvisible in the interspacesbetweenthe revolving^costae.

Habitat.—

OS

South

Coronado

Island in 7 to 10 fathoms, Dr. Fred Baker. U. S. Nat. Mus. Cat. No. _223,291. Also off

San

_Diego in 20 fathoms.

Liotia acuticostata,

new

var. stearnsii.

Resembling acuticostata but smaller, with

more numerous and

^less prominentspiral cords. Height, 2.3; width, 2.3

mm.

Habitat.—Gulf of California, Stearns. U. S. Nat. Mus. Cat. No.

47,062.