CYCLOSTOMA. 201 



seventy-nino species, one of which is the only true repre- 

 sentative of the group inhabiting- the British Isles. With 

 a doubt, we have inchided as its associate in the same family, 

 the curious genus Acme. 



CYCLOSTOMA. Montfort. 



Shell globoso-turbinate, ovato-turreted or depressed, 

 often strong, variously sculptured : aperture oval, with a 

 simple, straight, or expanded peristome. Operculum sub- 

 oval, testaceous, plane, exhibiting four or five whorls, its 

 margin simple, its nucleus subeccentric. 



Animal with a proboscidiform muzzle, two subulate 

 tentacles, eyes at their external bases ; foot ovate ; mantle 

 quite free ; sexes distinct. 



Even in its most restricted sense, this genus includes no 

 fewer than eighty species, the great majority of which are 

 tropical. 



C. ELEGANS, Muller. 



Plate ex XI I. fig. 3. 



Turbo reflexus, LiNN. Syst. Nat. ed. 12, p. 1258 (inadequately described) from 

 type. 



Nerita dcyans, Muller, Verm. Hist. vol. ii. p. 177. 



Tiirho tumidns, Penn. Brit. Zool. ed. 4, vol. iv. p. 128, pi. 82, f. 110. 

 „ slriatus, Da Costa, Brit. Conch, p. 8G, pi. 5, f. 9. — Donov. Brit. Shells, 



vol. ii. p. 59. 

 „ elccjans, Mont. Test. Brit. vol. ii. p. 342, pi. 22, f. 7. — Maton and Rack. 

 Trans. Linn. Soc. vol. viii, p. 167. — Rack. Dorset Catalog, 

 p. 50, pi. 21, f. 9.— TuRT. Conch. Diction, p. 207, f. 48, 49. 



Cydostoma „ Drap. Moll. Ter, et Fluv. France, p. 32, pi. 1, f. 5, 8. — Fleming, 

 Brit. Animals, p. 257. — Jeffr. Trans. Linn. Soc. vol. xvi. 

 p. 362. — Berkeley, Zool. Journ. vol. iv. p. 278, anatomy. — 

 Turt. Manual L. and F. W. Shells, p. 93 (ed. Gray, p. 275), 

 f. 75. — Thompson, Ann. Nat. Hist. vol. vi. p. 126. — Brown, 

 Illust. Conch. G. B. p. 34, pi. 14, f. 28, and pi. 18*, f. 29.— 

 Brard, Coq. Envir. Paris, p. 103, pi. 3, f. 78. — C. Pfeif. 

 Deutsch. Land und SUssw. Moll. pt. 1, p. 74, pi. 4, f. 30, 31.— 



VOL. IV. D D 



