234 MANUAL OF THE MOLLUSCA. 



Distribution, 30 species. Greenland, Britain, West Indies, 

 Cape, Australia, Pacific, West America. 



Erato, Eisso. 



Etymology, Erato, the muse of love-songs and mimicry. 

 Type, E. laevis, PI. VII., Fig. 24. 



Shell minute ; like margineUa ; lips minutely crenulated. 

 Animal like trivia. 



Distribution, 11 species. Britain, Mediterranean, West Indies, 

 China. 

 Fossil, 2 species. Miocene — . France, Britain (Crag). 



Oyultjm, Lam. 



Etymology, diminutive of ovum, an egg. 



Synonym, Amphiceras, Gronov. 



Types, 0. Ovum, PI. YII., Fig. 25. 0. gibbosa and verrucosai 



Shell like cyprcea ; inner lip smooth. 



Distribution, 36 species. Warm seas. West Indies, Britain, 

 Mediterranean, China, West America. 



Fossil, 11 species. Eocene—. France, &c. 



Sub-genus. Calpurna, Leach. 0. volva ("the "weaver's 

 shuttle "). Aperture produced into a long canal at each end. 

 Foot narrow, adapted for walking on the round stems of the 

 gorgonioe, &c., on which it feeds. C. patula inhabits the south 

 coast of Britain, it is very thin, and has a sharp outer lip. 



Calpurnus, Montfort (name) == Ovulum verrucosum. 



Volva (Fleming) = Ovulum patulum {Calpurna, Leach). 



Radius (Montfort) Schum. = Ovulum volva 



Section B. Holostomata. Sea-Snails. 



Shell spiral or limpet- shaped ; rarely tubular or multi valve : 

 margin of 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. 68), 

 gills pectinated or plume-like, placed obliquely across the back, 

 or attached to the right side of the neck ; neck and sides fre- 

 quently ornamented with lappets and tentacular filaments. 

 Marine or fresh-water. Mostly phytophagous.* 



• These "sections" are not verj' satisfactorj', but they are better than any others 

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

 proso-branchiata. Natica and scriJaria liave a retractile proboscis. Pirena has a 

 notched aperture, and aporrhais, a canal. 



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