A new proserpinoid land shell from Brazil

VOL. _XVIII, PP. 201-202 SEPTEMBER 2, 1905

PROCEEDINGS

OFTHE

BIOLOGICAL SOCIETY OF WASHINGTON

A NEW PROSERPINOID LAND SHELL FROM BRAZIL.

BY WILLIAM HEALEY DALL.

The

_genus

_Cyane H. Adams,

described in 1870, ^issaidtodif fer

from

_{-ordinary Proserpina}

by having

^the columella truncate

and no

parietal or palatal laminae. ^It has not been _figured

and

I

have

not seen specimens, but

from

the characters of a shell about to be described, ^it

may

^be merely, ^as

Tryon

concluded, a subordinate subdivisionof Prosefpina.

From

the calcareous

banks

of the arroyo ^ofthe Rio Chico at Paraguassii, State ^of Bahia, Doctor Orville A.

Derby

^obtained

ji small apparently ^subfossil land _shell,

which

has been sub mittedto

me

for

examination by

^Doctor

H. von

Ihering, Director ofthe

Museu

Paulista, ^at Sao Paulo, ^Brazil.

The _specimen

is of very

much

the

same

size

and

habit as Proserpina depressa Orbigny,

from

_Cuba,in

which

the columella,

if it

may

^be so called, descends in

an

even curve

from

_{the pari}

etal wall until it

merges

imperceptibly ^{in the basal}

margin

^of the aperture

and

bears at right angles^{to itself} a small _lamella,

which

often lags behind so as to be but little visible

from

in front of the aperture.

But

in the case of theshell

from

Brazil the lamella is

prominent and

_strong

and

thecurveofthe

colum

ella is taken

up by

^it parallel to the base of the aperture

and

so near the basal

margin

^that only a

narrow

notch exists be

tween them,

giving the ^{effect of}

an

_oblique truncation of the pillar. This leadsto the surmise, in the absence of a _figure or

:',f> PROC.BIOL. Soc. WASH.,VOL. XVIII, ^1905. (201)

202 Doll

A ^New

Proserpinoid

Land

Shell

from

^Brazil.

full diagnosis of Cyane, ^that the chief character

upon ^which Adams

based his

genus may ^have

^beenofalikenature, in

which

case itcould hardly be accounted ^ofgeneric value.

From

_Cyane, however, the present species ^differs in preserv ing aparietal lamella; and, ^as Bland, ^Pfeiffer

and

others

have

considered differences of the

arrangement and number

of the lamella? of the aperture^{as sufficient characters for} subdivisions ofthe genus, the ^{Brazilian shell}

might

^be regarded^asconstitut ing the type ^of a section or subdivision with those characters,

which might

^{be called} Staff^ola.

Proserpina (Staffola) derbyⁱ sp.nov.

Shell _small, depressed, pale yellowish,

when

fresh probably polished, with anaxial sculpture of fine,non-punctate,sharply incised^striaenearly parallel totheincrementallines,butvisibleonly underconsiderable

mag

nification; spire depressed,domelike,the sutures obscure, theprotoconch large,followedby^fivewhorls; baseflattish,imperforate, notexcavated in the center; aperture semilunar, outer lip thin,sharp,advancing slightly from thesutureand_slightlyexcavated_justbeforeitjoinsthepillar;parietal wallwitha_singlelamellaaboutone-third of the

way

^{from the} pillar to the suture;periphery^oftheshell inflatedlyrounded; thearmatureofthe pillar has been already described; height ofshell, 2.5;max.diam.,^5.0;

min. _diam.,4.0

mm.

The

shellisinsuch acondition thatitmight be^eitheraPleistocenefos silora^"dead^"shell washedfrom a higher^levelandstranded by falling waterinthecreek.

The Proserpinidre have hitherto been

known

_{only from} the _Antilles, Mexico, middle Americaandthe shores adjacent^tothe Caribbean,except inthe case ofCyane^blandianaAdams, which wasdescribed from Eastern Peru. Thepresence ofa_{species in}the State ofBahia is therefore avery interesting additiontotheknowledge ^of the geographical distribution of membersofthis group. Even if fossil,^itcarriestherange 1,000 miles^to thesouth and east, andadds weight ^{to theconnection} which has been already^insistedonbetween the Antilleanfauna and that of the Eastern portion ofSouthAmericasouth of theAmazonas.