CONCHOLOGY. 



gravity is much greater than that of the 

 water)inthissingular position: Itoccasion- 

 ally crawls to the margin of the water to 

 inhale a supply of air ; with this object the 

 foramen is protruded to the surface, and 

 opened with an audible snapping sound, 

 similar to that produced by the nib of a 

 pen. 



There is a species of this genus that 

 resembles ;the Stagnalis of Europe : we 

 have named it LymnaeaJwg-wZarw. Whorls 

 about six, tapering ; mouth within often 

 brownish, lip white, column a little con- 

 tracted in the middle; we have not a 

 good specimen to describe or figure. 



2. L. Heterostropha. Shell sinistral, sub- 

 ovated ; colour, pale yellow, chesnut or 

 blackish ; whorls four, the first large, the 

 others very small, terminating rather ab- 

 ruptly in an acute apex ; aperture large, 

 somewhat oval, three-fourths 'of the 

 length of the shell, or rather more ; 

 within of a pearly lustre, often blackish ; 

 lip a little thickened on the inside, and 

 tinged with dull red. 



Inhabits with the first species, and al- 

 most as numerous. 



Plate 1. fig. 6. 



Animal resembles that of L. Catasco- 

 pium, but is of a darker colour and longer 

 than its shell; thetentacula also are longer 

 and setaceous ; tail acute. 



3. L. Subcarinata. Shell with three 

 whorls, which are rounded, and subcari- 

 nated, reticulated with striae 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 subcarinaon 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. Virgi-nica. 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 revolving 

 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 base. 



Length one inch ; breadth two-fifths of 

 an inch. 



Plate 2. fig 4. 



Lister's conch, tab. \\7.fg. 7. Thebasi- 

 lar part of the lip in this figure is defi- 

 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 

 readily discoverable in clear water by the 

 channel it forms in the mud. 



Specimens of this shell, brought from 

 the Lakes and their vicinity by JWr. Le- 

 sueur, had the revolving lines very ob- 

 scure or obsolete. 



In Gmelin's edition of Syst. Nat. p. 

 3505, reference is made to Lister's figure 

 as Buccinum Virgineum, and as the de- 

 scription agrees tolerably well with our 

 shell, it may be, and probably is, the 

 same ; with this supposition, and a desire 

 to avoid a useless multiplication of names, 

 the present designation is given ; though 

 we do not think it correct, notwithstand- 

 ing the universal custom, to apply a spe- 

 cific name drawn from the locality of the 

 specimen, or from the name of a person, 

 unless such designation shall be expres- 

 sive of the character of the animal, 

 plant, &c. described, which we presume 

 can rarely be the case. Lister's lower 

 figure of tab. 109 also resembles 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. S/iells. tab. 87, ffeKx Vivi- 

 para. 



Lister, conch, tab. 126, fig. 26 / Cochleee 

 vivipara fasciata. 



