SPECIES.
I. • P. Limosa. Shell conic, subumbili cate, dark horn coloured, generally in crusted with a blackish irregular covering on the spire, and sometimes on the body, which completely obscures the obsolete. ly wrinkled epidermis ; aperture ovate orbicular; suture impressed.
Length three-twentieths, breadth one tenth, of an inch.
Journ. 4cad. Nat. Sciences, vol. i. p.125.
Animal whitish ; head brown ; mouth, tentacula, orbits, and vita on each side of the neck, white ; tentacula filiform, more than half as long as the base of the ani. mal; rostrum about half• as long as the tentacula, annulate, with darker lines above ; foot white, brownish above, short, suboval, truncated before, and rounded behind.
Extremely numerous on the muddy shoies of the rivers telaware and Schuyl kill, between.high and low water marks.
2. P. lapidaria. Shell turreted, suborn bilicate, with six volutions, which are ob soletely wrinkled across. Suture im pressed. Aperture longitudinally ovate orbicular, operculated, rather mere than one-third of the length of the shell.
Length about one-fifth of an inch.
Jaurn. Acad. Nat. Sciences, vol. i. p. 13.
Inhabitant not so long as the shell, pale; head elongated into a rostrum as long as the tentacula, and emarginate at tip; ten tacula two, filiform, acuminated at tip, short ; eyes prominent, situated at the external or posterior base of the tentacu la; base or foot of the animal dilated, oval, obtuse before and behind.
Found under stones, &c. in moist situa tions, on the margins of rivers. Like those of the genera 1,3 mnxa and Planor bis this militia' possess the faculty of crawl ing on the surface of the water, in a re versed position, the shell downward.
3. L. Snhcarinata. Shell with three whorls, which are rounded, and subcari nated, reticulated with strix and wrin kles, sometimes without the stria ; suture deeply impressed ; apex truncated and re-entering ; aperture more than half of the length of the shell, oval ; elevated lines or subcarina on the body two, three, and sometimes none.
Length half of an inch: breadth four tenths.
Inhabits with the preceding species. Plate 1. fig. 7.
Animal viviparous, with a Chesnut, coriaceous, operculum, white spotted with orange; head pale orange, not ex tending beyond the shell ; tentacula dark er, short, subulate ; eyes situated at their base, elevated, black and conspicuous ; base of the animal much advanced, broad, truncate, purplish before, tail rounded behind.
4. L. Virginica. Shell tapering, olive, horn colour or blackish, under the epi dermis tinged with green ; whorls seven, but little rounded, crossed by curved wrinkles on the spire, and reclivate ones on the body : a dull red line revolves near the base of the whorls, and on the middle of the body a reddish-black broad er line, from within the upper angle of the aperture, runs parallel with the other, and terminates near the base. Aper ture subovate, more than one third as long as the shell, lip not thickened, but dilated at the base.
Length one inch ; breadth two-fifths of an inch.
Plate 2. fig. 4.
Lister's conch. tab. 117. fig. 7. The basi• lar part of the lip in Lister's figure is defl. cient.
Inhabitant bluish-white beneath, with orange clouds each side of the mouth ; above pale orange, shaded with dusky and banded with numerous black interrupted lines; mouth advanced into a rostrum as long as the tentacula, which are darker at the base, and setaceous ; base of the animal with an undulated outline.
It often occurs in our rivers, and is rea dily discoverable in clear water by the channel it forms in the mud.
Specimens of this shell, brought from the Lakes and their vicinity, by wit/i•. Le sueur, had the revolving lines very ob scure or obsolete.
Lister's lower figure of tab. 109, also re sembles this shell.
5. L. Vivipara. Shell subconic, with six rounded whorls ; suture impressed, colour olivaceous or pale, with three red brown bands, of which the middle one is generally smallest ; whorls of .the spire with but two, aperture suborbicular, more than half length of the shell.