SPECIES.
1. P. Trivolvis. Shell sinistral pale yellow, brownish or chesnut colour, sub carinate above and beneath, particularly in the young shell ; whorls three or four, striate across with fine, raised, equi-dis. t ant, acute lines, forming grooves between them. Spire concave ; aperture large, embracing a considerable portion of the body whorl, within bluish white ; lip a lit tle thickened, internally, and of a red or brownish colour, vaulted above ; umbili cus large, exhibiting the volutions.
Length one-fourth of an inch ; breadth one-half of an inch.
Animal aquatic, dark ferruginous, with very numerous, confluent, pale yellowish points; tentacula long, setaceous, with confluent points ; foramen on the left side.
That ingenious naturalist, Mr. C. A. Lesueur, found this species of a much larger size in French Creek, near Lake Erie ; breadth three fourths of an inch nearly ; colour almost black, purplish red within the mouth.
Plate 2. fig. 2.
Cochlea, trim orbium. Lister. Conch, tab. 140. fig. 46.
Lister figures this shell pretty accu rately, and it is referred to in Gmelin's Edit. of Syst. Nat. p. 3615, as Albella, but it is certainly not that species.
2. P. Bicarinatas. Shell sinistral, pale yellow or brownish, subcarinate above, and beneath translucent. Spire retus umbilicate, forming a cavity as deep as that of the base. Aperture large, em bracing a considerable portion of the body whorl, and much vaulted above. Within red brown, with two white lines corresponding with the caring. Whorls three, wrinkled, and with minute revolv ing lines.
Length one-fourth of an inch ; breadth nearly half an inch.
Inhabitant aquatic, ferruginous, with numerous yellowish dots ; tentacula dot ted and flexuous.
Plate 1. fig. 4.
Resembles the preceding species in its outline, but differs from that shell in the remarkable umbilicate appearance of its spire ; it is also destitute of those fine parallel raised lines, and is furnished with minute stria, never visible in P. Tri
volvis, the superior part of the lip is more vaulted, and the caring more visible.
3. P. Parvus. -Shell horn colour or blackish ; whorls four, crossed by minute wrinkles ; concave above and beneath, and equally exhibiting the volutions; body generally subcarinate on the margin ; lip rounded, and not vaulted above nor thickened ; mouth within bluish white.
Breadth one-fifth of an inch.
Animal aquatic brown, tentacula long, 'inform, whitish, with a darker central line, tail rounded.
Plate 1. fig. 5.
Probably the same species with that figured by Lister, tab. 139. fig. 45; it is very numerous in the river Delaware, in company with the two preceding shells.
4. P. Glabratus. Shell sinistral ; whorls about five, glabrous, or obsoletely rugose, polished, destitute of any appearance of carina ; spire perfectly regular, a little concave ; umbilicus large, regularly and deeply concave, exhibiting all the volu tions to the summit ; aperture declining, remarkably oblique with respect to the transverse diameter.
Breadth nearly nine-tenths of an inch. Journ. Acad. .Wat. Sciences, vol. i. p. 280. Inhabits South Carolina.
Presented to the Academy by Mr. L'Hermenier of Charleston, ari intelligent and zealous naturalist; he assured me that this species inhabits near Charleston. It somewhat resembles large specimens of the P. Trivolvis, but differs in the total absence of nd in having a more smooth and polished surface, as well as a declining and more oblique aperture, and a more profound and much more regu larly concave umbilicus.