36 MOLLUSCA. 



not tumid ; the side of the columella is almost concave. The shell will 

 not receive the entire animal, and it might almost be considered as a 

 large-shelled Testacella. Its inferior tentacula are very small, and it 

 lives on the plants and shrubs which line the banks of rivulets, a cir- 

 cumstance which has caused the genus to be considered as amphi- 

 bious*. 



It is necessary to separate from the genus Turbo of Linn, and refer 

 to the genus of terrestrial Helices the following : 



CLAUSILIA, Drap. 



The shell is long, slender, and pointed, the last whorl, in the adult, 

 narrowed, compressed, slightly detached, and terminated by a com- 

 plete aperture with a tumid margin, frequently dentated or furnished 

 with laminae. In the contraction of the last whorl we usually find a 

 little plate bent into an. S, the use of which to the living animal is 

 unknown. 



The species are very small, living in mosses at the foot of 

 trees, &c. A great many of them are reversed-)-. 

 It is also necessary to separate from the Bulla of Linn, and place 

 here 



ACHATINA, Lam. 



In which the aperture of the oval or oblong shell is higher than it is 

 broad, as in the Bulimi, but it wants the tumid margin ; the ex- 

 tremity of the columella also is truncated, the first indication of the 

 emarginations which we shall find in so many marine Gasteropoda. 

 These Achatinse are large Helices, which devour trees and shrubs in 

 hot countries {. 



Montfort distinguishes those, in the last whorl of which we find a 

 callus or peculiar thickening, Liguns, Montf.|| ; this whorl is propor- 

 tion ably lower in them than in the others : 



And those in which the extremity of the columella is curved to- 

 wards the inside of the aperture, Polyphemus, Montf. ; the last 

 whorl is higher, The 



* Succinca amphibia, Drap., IV, 22, 23 (Helix putris, L.) ; S. oblong a, Ib., 24. 

 The genera COCHLQHYDRA, F^russ., LUCINA, Oken, TASSADE, Huder, cor- 

 respond to the Succinese. M. Delarnark at first styled them AMPHIBULIMI. The 

 Amphibulime encapuchonnt, Lam., Ann. du Mus. VI, Iv, l,may also form a Testa- 

 cella. 



t Turbo perversus, L., List., 41, 39 ; T. bidens, Gm., Drap., IV. 5, 7 ; T. pa- 

 pillaris, Gm., Drap., Ib., 13 ; and the other Clausiliae of Drap., figured on the same 

 plate; Bulimus retusus, Oliv., Voy., XVII, 2; Bui. inflatus, Ib., 3; Bui. teres, 

 Ib., 6 ; Bui. torticollis, Ib., 4, a, b ; Turbo tridens, L., Chemn., IX, xii, 957 ; 

 Clausilia collaris, F^russ., List., 20, 16, 



J Bulla zebra, L. Chemn., IX, ciii. 875, 876; cxviii, 1014 1016; Bulla 

 achatina, Ib., 1012, 1013; Bulla purpurea, Ib., 1018; Bulla dominicensis, Id., 

 CXVII, 1011: Bulla stercus pulicum, CXX, 1026, 1027; Bulla Jtammea, Id., 

 CXIX, 1021 1025; Helix tenera, Gm., Ib., 1028, 1030; Bulimus bicarinatus, 

 Brug., List., 37 ;Mtlanie buccino'ide, Oliv., Voy., XVII, 8. 



|| Bulla virginea, L., Chemn., IX, cxvii, 1000, 1003 ; X, clxxiii, 1682 3. 



Bulimus </lans, Brug., Chemn., IX, cxvii, 1009, 1010. 



