GASTEROPODA. 



115 



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



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

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



Distr., 6 sp. W. Indies, China, Gallapagos. (20 fras.) 



Fossil, 3 sp. Miocene. 



CITHARA, Schumacher. 



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



Type, cancellaria citharella, Lam. (cithara striata, Schum.) 



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

 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 genus were discovered by Mr. 

 Cuming, in the Philippine Islands. 



CASSIDAEIA, Lam. 



Etym., cassida, a helmet. 



Syn., morio, Montf. Sconsia, Gray. 



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



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



Distr., 5 sp. Medit. 



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



Fig. 71.* 



DOLIUM, Lam. Tne tun. 

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



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

 outer lip crenated. No operc. 



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



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

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



