934 MANUAL OF THE MOLLUSCA. 
Distribution, 30 species. Greenland, Britain, West Indies, 
Cape, Australia, Pacific, West America. 
ERATO, Risso. 
Etymology, Erato, the muse of loye-songs and mimicry. 
Type, HK. levis, Pl. VII., Fig. 24. 
Shell minute ; ike marginella ; lips minutely crenulated. 
Animal like trivia. 
Distribution, 11 species. Britain, Mediterranean, West Indies, 
China. 
Fossil, 2 species. Miocene—. France, Britain (Crag). 
Ovutum, Lam. 
Etymology, diminutive of ovwm, an egg. 
Synonym, Amphiceras, Gronoy. 
Types, O. Ovum, Pl. VII., Fig. 25. O. gibbosa and verrucosa. 
Shell like cyprea ; inner lip smooth. 
Distribution, 36 species. Warm seas. West Indies, Britain, 
Mediterranean, China, West America. 
Fossil, 11 species. Hocene—. France, &c. 
Sub-genus. Calpurna, Leach. O. 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 
gorgonice, &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. HonosToMATA. Sea-Snails. 
Shell spiral or limpet-shaped; rarely tubular or multivalye: 
margin of the aperture SURUS 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 Be 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 very satisfactory, but they are better than any others 
yet proposed, and they are convenient on account of the great extent of the order 
sroso-branchiata. Natica and scalaria have a retractile proboscis. Pirena has a 
tched aperture, and aporrhais, a canal, 
