122 MANUAL OF THE MOLLUSCA. 



Trivia, Gray. C. europsea, PL VII., fig. 23 ; fig. 76, and 15, B 

 Small shells with strise extending over the back. (Uncini ; 1st denticulat 

 2, 3, simple.) 



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

 America. 



ERATO, Risso. 



Etym., Erato, the muse of love-songs and mimicry. Type, E. Isevis 

 PL VII., fig. 24. 



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

 trivia. 



Distr., 8 sp. Brit., Medit., W. Indies, China. 



Fossil, 2 sp. Miocene . Trance, Brit. (Crag.) 



OVULUM, Lam. 



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



Types, 0. ovum, pi. VII., fig. 25. O. gibbosa and verrucosa. 



Shell) like cyprcea; inner lip smooth. 



Distr., 36 sp. Warm seas. W. Indies, Brit., Medit. China, W. America 



Fossil, 11 sp. Eocene . France, &c. 



Sub-genus, calpurna, Leach. O. volva (" The weaver's shuttle"). Aper. 

 ture produced into a long canal at each end. Toot narrow, adapted fo] 

 walking on the round stems of the gorgonice, &c., on which it feeds. C 

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

 lip. 



SECTION B. HOLOSTOMATA. Sea-Snails. 



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

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



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

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

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

 the neck ; neck and sides frequently ornamented with lappets and tentaculai 

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



FAMILY I. NATICIDJD. 



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

 lip, acute ; pillar often callous. 



Animal, with a long retractile proboscis ; lingual ribbon linear ; rachw, I 

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

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



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

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

 proso-branchiata. Natica and scalaria have a retractile proboscis. Pirena has 

 notched aperture, and aporrhais, a canal. 



