CONCHOLOGY. 



orbicular, operculated, rather mere than 

 one-third of the length of the shell. 



Length about one-fifth of an inch. 



Journ. 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 Lymnaea and Planor- 

 bis this animal possess the faculty of crawl- 

 ing on the surface of the water, in a re- 

 versed position, the shell downward. 



3. L. Subcarinata. Shell with three 

 whorls, which are rounded, and subcari- 

 nated, reticulated with strix and wrin- 

 kles, sometimes without the striae ; 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 hftlf 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 carved 

 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. \\7.fg. 7. The basi- 

 ]ar part of the lip in Lister's figure is defi- 

 cient. 



VOL. rv. 



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 wilh 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 Mr. 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 the length of the shell. 



Plate 2. fig. 5. 



Donov. Brit. Shells, tab. 87, Helix Vivi- 

 para. 



Lister, conch, tab. 126, Jig. 26 / Cochlex 

 vivipara fasciata . 



It is doubtful whether or not this is the 

 same as the Vivipara, but it certainly ap- 

 proaches very near to it; we however 

 refer it to that species until a specific dif- 

 ference can be indicated, which at pre- 

 sent we are unable to do ; the spire of 

 this species is rather more obtuse, and the 

 suture not so deeply impressed, as in the 

 figures of the European specimens above 

 mentioned. 



6. P. JDissimilis. Shell conic, dark 

 horn colour or blackish ; whorls about 

 three, with obsolete, distant wrinkles, 

 and an abrupt, acute, prominent, carina- 

 ted line, which revovles on the middle of 

 the body whorl, and is concealed on the 

 spire by the suture ; suture not indented, 

 aperture oval, haH" as long as the shell, 

 within sanguineous beneath the carina, 

 and at base, and apex ; columella emargi- 

 nated, a little flattened at the base. 



Length about two-fifths of an inch. 



far. Ji. Carina obsolete on the ventral 

 portion of the body whorl. 



Var. B. Carina distinct on the spiral 

 whorls, owing to their more oblique revo- 

 lution. 



The surface of the whorls of the spires 

 is generally covered with inequal calca- 

 reous matter, resembling a fortuitous ac- 

 cumulation of mud or earth on that part, 

 but which appears to be superposed by 

 the animal, probably with the intention of 



C 



