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 (snhg. Synaptocochlea, 



Ni'phonici), shell depressed, spirally ribbed, spire short, operculum 

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

 last whorl keeled, sinuate in front ; Stomatia, spire short, surface 

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

 surface smooth, aperture very large : Broderipia, shell patelliform, 

 spiral apex often lost. 



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

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

 filament, shell depressed, umbilicated, not nacreous. Eocene 



. Principal genera : Cyclostrema, Tcinostoma, 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), Crossostoma (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.) Trochinae. — Frontal lobes present, 

 lateral teeth ( = side centrals) 5 only, 

 no jaws, peristome incomplete. Prin- 

 cipal genera : Trochus (subg. Cardi- 

 nalia, Tcctus, Infundihulum, Clan- 

 culus), Monodonta (subg. Diloina), 

 Fig. 210. — Monodonta canalifera Cccntharidus (subg. Bctnhivia, Tha- 



Lam New Ireland. (After Quoy Igtia), Gaza (subg. MicrOC/azu), 

 andGaimard.) /' ^ J= '^ / 



Callogaza, Bemhix, Chlorostoma. (ii.) 

 Gihlndinae. — Frontal lobes and jaws present, laterals often 

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

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

 Trochiscus, Livona, Photinula, Margarita, Solariella, Calli- 

 ostoma, Turcica, Basilissa, Btichelus (subg. Olivia, Perrinia). 

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



