36 MOLLUSCA. 



not tumid ; tlie 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 timiid 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 veiy small, living in mosses at the foot of 

 trees, &c. A gi-eat many of them are reversedf . 

 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 tvimid margin ; the ex- 

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

 emarginations which we shall find in so many marine Gasteropoda. 

 These Achatinae 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 



* Succineo amphibia, Drr.p., IV, 22, 23 {Helix put ria, L.) ; — S. oblunga, lb., 24. 

 — The genera Cochlcthydra, F^ru?s., Lucina, Oken, Tassade, Huder, cor- 

 respond to the Succincfe. M. Delamark at first styled them Amphibulimi. The 

 Amphibulime encapuchonni, Lam., Ann. du Mus. VI, Iv, 1, may also form a Testa- 

 ceUa. 



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

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

 plate; — BuUmus retusus, Oliv., Voy., XVII, 2 ; — Bui. infiatus, lb., 3; — Bui. teres, 

 lb., 6 ; — BuL torticollis, lb., 4, a, b ; — Turbo tridens, L., Chemn., IX, xii, 957 ; — 

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



+ Bulla zebra, L. Chemn., IX, ciii. 875, 876; rxviii, 1014 — 1016; — Bulla 

 achatina, lb., 1012, 1013; — Bulla purpurea, lb., 1018; — Bulla dominicensis, Id., 

 CX\'II, 1011: — Bulla sternis pulicum, CXX, 1026, 1027; — Bulla flammea, Id., 

 CXIX, 1021 — 1025; — Helix fenera, Gm., lb., 1028, 1030 ■,—Bulimus bicarinafus, 

 Brug., List., 37 ; — Minnie buccinoide, Oliv., Voy., XVII, 8. 



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



§ Bulitmis glrnis, Brug., Chemn., IX, cxvii, 1009, 1010. 



