GASTEROPODA. 115 



Type, 0. oniscus ; 0. cancellata, pi. VI., fig. 15. 



Shell, with a short spire, and a long narrow apertiu'e, slightly truncated 

 in front ; outer lip thickened, denticulated ; inner lip granulated. 



Bistr., 6 sp. W. Indies, Cliina, Gallapagos. (20 fms.) 



Fossil, 3 sp. Miocene. 



CiTHARA, Schumacher. 



Etym., cithara, a guitar. Sy7i., mangelia, Reeve (not Leach). 



Type, canceUaria cithareUa, Lam. (cithara striata, Schum.) 



Shell, fusiform, polished, ornamented with regular longitudinal ribs; 

 aperture linear, truncated in front, slightly notched behind ; outer lip mar- 

 gined, denticulated within ; inner lip finely striated. Operc. ? 



Distr., above 50 sp. of this pretty little g^nus were discovered by Mr. 

 Cuming, in the Philippine Islands. 



Cassidakia, Lam. 



Etym., cassida, a helmet. 



Syn., morio, Montf. Sconsia, Gray. 



Type, C. echinophora. PL VI., fig. 13. 



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



Distr., 5 sp. Medit. 



Fossil, 10 sp. Eocene — . Brit., France, &c. 



Fig. n.* 

 DoLiUM, Lam. The tun. 

 Type, D. galea. PI. VI., fig. 12. 



Shell, ventricose, spirally furrowed ; spire small ; aperture very large ; 

 outer lip crenated. No opcrc. 



Distr., 14 sp. Medit., Ceylon, China, Australia, Pacific. 



* D. perdix, L. sp. ^ nat. size (after Quoy). Vanicnro, Pacific. The proboscis 

 is exserted, and the siphon recurved over the front of the shell. 



