408 DIOTOCARDIA— RHIPIDOGLOSSA chap. 



Fam. 1. Cocculinidae. — A single cervical cteniclium, foot 

 broad, no eyes, shell patelliform, with caducous spire. Single 

 genus, Cocculina. Deep water. 



Fam. 2. Stomatellidae. — A single (left) ctenidium, front third 

 free, shell nacreous, spiral or patelliform, depressed, last whorl 



large. Jurassic . Genera: Stomatella (^ubg. Synaptococlilea^ 



Ni'phonia)^ shell depressed, spirally ribbed, spire short, operculum 

 present; Phaneta^ fluviatile only, shell trochiform, imperforate, 

 last whorl keeled, sinuate in front; Sto?natia^ spire short, surface 

 tubercled or keeled, no operculum : Crena, shell haliotis-shaped, 

 surface smooth, aperture very large : Broderipia^ shell patelli- 

 form, spiral apex often lost. 



Fam. 3. Cyclostrematidae. — Tentacles ciliated, thread-like, 

 snout bilobed, foot truncated in front, angles produced into a 

 filament, shell depressed, umbilicated, not nacreous. Eocene 



. Principal genera : Cyclostrema^ Teinostoma^ Vitrinella. 



Fam. 4. Liotiidae. — Epipodial line with a lobe behind each 

 eye-peduncle, shell solid, trochiform, longitudinally ribbed or 

 trellised, aperture round, operculum multispiral, hispid, corneous, 



with a calcareous layer. Silurian . Principal genera : 



Liotia, Craspedostoma (Silurian), Orossostoma (Jurassic). 



Fam. 5. Trochidae. — Snout short, broad, frontal lobes often 

 present, epipodial line furnished with cirrhi; shell nacreous, 

 variously spiral, operculum corneous, multispiral, nucleus central 



(Fig. 182, p. 268). Silurian . 



(i.) Trocliinae. — Frontal lobes present, 

 lateral teeth (= side centrals) 5 only, 

 no jaws, peristome incomplete. Prin- 

 cipal genera: TrocJius (subg. Oardi- 

 nalia^ Tectus, Infundihidum^ Clan- 

 culus'), Monodo7ita (subg. B'doma)^ 

 Fig. 270. — Monodonta canaii- Caiitliavidus (subg. BanMvia, Tha- 



fera Lam., New Ireland ^^^-^^ Q.^^^ q^^i Mlcrogaza}, Cal- 



(After Quoy and Gaimard.) ^' > ^ ^ ^^ x 



logaza^ Bemoix, Chlorostoma. (ii.) 

 G-ihhulinae. — Frontal lobes and jaws present, laterals often 

 more than 5, peristome incomplete. Principal genera : Gih- 

 hula (subg. Monilia^ Aphanotrochus, Enida)^ Minolia^ Circulus, 

 Trochiscus, Livona^ Photinida^ Margarita^ Solariella^ Calli- 

 ostoma. Turcica^ Basdissa, Euchelus (subg. Olivia., Perrinia). 

 (iii.) Delphinulinae. — No frontal lobes, jaws present; shell solid. 



