GASTEROPODA. 183 



Animal with a squarish, disk-like head, eyes sessile in the centre ; mantle not 

 investing; a posterior lobe; lateral lobes enveloping. (Pl.XIV. fig. 8, not 7)- 



AcERA, Midler. 



Tifpe, A. bullata, PI. XIV. fig. 9. Etym. Akeros, hornless. 



Shell thin, flexible, globosely ^cylindrical, spire truncated, whirls chan- 

 nelled ; aperture long, expanded and deeply sinuated in front, outer margin 

 disunited at the suture ; columella open, exposing the whirls. 



Animal with a short and simple head-lobe, truncated in front and eyeless ; 

 lateral lobes nearly concealing the shell ; lingual teetb hooked and serrulate, 

 laterals about 40, narrow, claw-shaped ; gizzard armed with horny teeth. 



Distr. 7 sp. Greenland, Brit. Medit. Zanzibar, India, New Zealand. 



A. bullata is found amongst weed, in 1 — 15 fms. water {Forbes). 



Cylichna, Loven. 



Tijpe, C. cylindracea, PL XIV. fig. 10. Syn. Bullina, Risso. 



Shell strong, cylindrical, smooth or punctate-striate ; spire minute or 

 truncated; apertm^e narrow, rounded in front; columella callous, with one 

 plait. 



Animal short and broad, not investing the shell ; head flattened, truncated 

 in front, witb sub-centrally immersed eyes, tentacular lobes more or less 

 united ; foot oblong, posterior and lateral lobes not much developed ; gizzard 

 armed; lingual teeth squarish, recurved and serrated, with 1 large and 5 or 

 6 small hooked laterals. 



Distr. 20 sp. U. States, Greenland, Brit. Red Sea, Australia. 



Fossil. Miocene — . Brit. 



Amphisphyra, Loven. 



Type. A. pellucida, Jobnst. {Amphi-sphyra, double hammer.) 



Syn. Utriculus (part) Brown. Rhizorus, Montf. Diaphana, Brown. 



Shell small, thin, ovate, truncated, spire minute papillary, aperture long. 



Animal entirely retractile into its shell; head wide, short, with lateral 

 triangular tentacles ; the eyes behind them minute, immersed ; muzzle 

 bi-lobed in front ; foot oblong, truncated in front, notched behind ; teeth 

 1.1.1, central quadrate, serrulate; laterals broad, hooked. 



Distr. 5 sp. U. States, Norway, Brit. Borneo, Mexico. 



'Aplustrum, Schumacher, 

 Type, Bulla aplustre, PI. XIV. fig. 11. Etym. Aplusire, a ship's flag. 

 .9^^?. Bullina, Per. Hydatina (physis) Schum. Bullinula (scabra) Beck. 

 5//^// oval, ventricose, highly coloured; spire wide, depressed; aperture 

 truncated in front ; outer lip sharp. 



Animal, with a very large foot, extending beyond the shell all round, and 

 capable of enveloping it ; a posterior -lobe reflected on the spire ; mantle not 

 investing ; tentacidar lobes large, oval, ear-shaped ; labial tentacles four ; eyes 



K 



