122 MA^^UAL OF THE MOLLUSCA. 



Trivia, Gray. C. eiiropsea, PI. VII., fig. 23 ; fig. 76, and 15, B. 

 Small shells wtli strise extending over the back. {Uncini ; 1st denticulate 

 2, 3, simple.) 



Distr., 30 sp. Greenland, Biit., W. Indies, Cape, Australia, Pacific, W. 

 America. ' 



Erato, Risso. { 



Etpn., Erato, the muse of love-songs and mimicry. Tj/pe, E. Isevis, \ 

 PL YII., fig. 24. ; 



Shell minute ; like marginella ; lips minutely crenulated. Animal, like j 

 trivia. < 



Bistr., 8 sp. Brit., Medit., W. Indies, China. I 



Fossil, 2 sp. IVIiocene — . France, Brit. (Crag.) ' 



OvuLUM, Lam. \ 



Etym., dimunitive of ovum, an egg. Syn., amphiceras, Gronov. j 



Types, O. ovum, pi. VII,, fig. 25. 0. gibbosa and ven-ucosa. \ 



Shell, like cyprcea ; inner lip smooth. ; 



Disir., 36 sp. Wann seas. W. Indies, Brit., Medit. China, W. America. 

 Fossil, 11 sp. Eocene — . Prance, &c. j 



Suh-genus, calpurna,'L&2icla..' 0. volva (" The weaver's shuttle")- Aper- 

 ture produced into a long canal at each end. Poot narrow, adapted for , 

 walkiug on the round stems of the gorgonia, &c., on which it feeds. 0. 

 patula inhabits the S. coast of Britain, it is very thin, and has a sharp outer 

 lip. 



SECTION B. HoLOSTOMATA. Sea-Snails. 



Shell, spiral or limpet shaped ; rarely tubular or multivalve : margin of 

 the aperture entire. Operculum, horny or shelly, usually spiral. 



Animal with a short non-retractile muzzle ; respiratory siphon wanting, j 

 or formed by a lobe developed from the neck (fig. 61), gills pectinated or ^ 

 plume- like, placed obliquely across the back, or attached to the right side of 

 the neck ; neck and sides frequently ornamented with lappets and tentacular I 

 filaments. Marine or fresh-water. Mostly phytophagous.* 1 



PAMILY I. NATICID.E. ^ 



Shell, globular, few- whirled ; spire small, obtuse ; aperture, semi -lunar ; i 



lip, acute ; piUar often callous, \ 



Animal, with a long retractile proboscis ; lingual ribbon linear ; rachu, 1 



toothed; uncini, 3 (similar to trivia, fig. 15, B.) ; foot very large ; mantle-lobes ' 

 largely developed, hiding more or less of the shell. Species aU marine. 



* These " sections" are not very satisfactory, but they are better than any others 

 yet proposed, and they are convenient, on account of the great extent of the order 

 prnso-hram-Mala. Natica and scalaria have a retractile proboscis. Pirena has 

 notched aperture, and aporrhais, a canal. 



