GASTEEOPODA. 225 



Fossil, 36 species. Eocene — . Chili, France. 



The queen-conch (C. madagascariensis) and other large 

 species are used in the manufacture of shell cameos, p. 38. The 

 periodic mouths {varices) which are very prominent, are not 

 absorbed internally as the animal grows. 



Oniscia, Sowerby. 



Etymology, oniscus, a wood-louse. 



Synonym, Morum, Bolten, 



Type, 0. oniscus; 0. cancellata. PL VI., Fig. 15. 



Shell with a short spire and a long narrow aperture, slightly 

 truncated in front ; outer lip thickened, denticulated ; inner lip 

 granulated. 



Distribution, 9 species. West Indies, China, Gallapagos, 

 United States. (20 fathoms). 



Fossil, 3 species. Miocene. United States, Domingo. 



Cassidaria, Lam. 



Etymology, cassida, a helmet. 



Synonyms, Morio, Montfort. Sconsia, Gray. 



Type, C. echinophora. PI. YL, Fig. 13. 



Shell ventricose ; canal produced, rather bent. No operculum. 



Distribution, 6 species. Mediterranean. 



Fossil, 10 species. Eocene — . Britain, France, &c. 



Bachybatheon, Gaskoin. 



Shell small, oblong, striated with lines of growth; spire 

 small, depressed, with channelled suture ; aperture with callous 

 denticulated lips, like Cypreea. 



Distribution, 3 species. 



Fig. 86. Dohum perdix. (Original). 



DoLiUM, Lam. The Tun. 



Tyjw, D. galea. PI. YL, Fig. 12. 



Shell yentricose, spirally furrowed ; sj)iro small ; aperture 

 very large ; outer lip crenated. No operculum. Teeth 3, 1, 3. 

 Fig. 86. The genus Macgillivrayia, formerly assigned to the 

 Atlantidse, belongs here. It comprises the larya forms of several 

 species of Dolium. 



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