128 NEW-YORK FAUNA — MOLLUSCA. 
(EXTRA-LIMITAL.) 
Genus Pirrena, Lamarck. Animal with an elongated rostrum: tentacles two, contractile, conic, 
annulated, with the eyes on peduncles at their external bases; foot short, oval, angular in 
front on each side; breathing-hole in the furrow, formed by the union of the mouth with the 
body. Fresh water. ‘Shell turreted; aperture longitudinal. Lip acute, witha distinct sinus 
at the base, and another at its junction with the body: base of the columella turned towards 
the right. Opercle horny, subspiral. 
P. scalariformis. (Savy, Ac. Sc. Vol. 5, p. 128.) Whorls rounded, with numerous elevated lines, ending 
the body-whorl by 5 — 6 revolving grooves: suture well impressed, with one of the grooves so near 
as to cause it to appear double; aperture rounded ; lip thickened, somewhat recurved ; sinus slight 
at the base, more obtuse above. No umbilicus. Color, pale, with several revolving reddish lines. 
Length, 0*9. Florida Keys. ; 
FAMILY CERITHIDAZ. 
ANIMAL with an elongated rostrum, without a trunk, but surmounted by a veil. Tentacles 
with the eyes about their middle, and externally. Inhabiting salt water. Sue. elongated, 
with the aperture much shorter than the remainder of its length. Opercle horny. 
Oss. This comprises a portion of the family Canalifera of Lamarck. 
GENUS CERITHIUM. Adanson. 
Animal elongated, spiral, with its rostrum depressed, and covered by a veil which is often 
fringed. ‘Tentacles distant, annulated, and bearing the eyes on a protuberance near the 
middle. Mouth without teeth, but with a small tongue. Foot short, oval, with a marginal 
furrow in front. Mantle forming on the left side a canal, or the rudiment of a syphon. 
Branchial cavity with a single gill, which is long and narrow. Shell turreted, elongated, 
almost always tuberculated. Aperture short, oval, oblique, with a short recurved often 
truncated canal. 
CERITHIUM SAYI. 
PLATE VIII. FIG, 167. 
(STATE COLLECTION.) 
Pasithea nigra. Totten, Am. Jour. Sc. Vol 26, p. 369, pl. 1, fig. 7. (Young.) 
Cerithiumreticulatum. Ip. Ib, Vol. 28, p. 352, fig. 8. 
(oA id. Apams, Bost. Journ. Nat. Hist. Vol. 2, p. 273. 
Cc. sayie Govcp, from Menke, Invertebrata of Mass. p. 278, fig. 183. 
Description. Shell small, acute, conic, thin. Whorls from six to eight, flat, with a dis- 
tinct shoulder, formed by a series of granules. Surface granular, from the crossing of slightly 
