PECTINIBRANCHIATA. 



Liotiidae. Liotia 



6 



Xcu/u-m (ficutus) Montfort (Parmophorus Blainv.), Australia, shell partly covered 

 by mantle ; Cemoria Leech, Riinula Defrance. Propilidium Forbes and H., and 

 Cocculina Dall, allied here. 



Section B. With one (left) ctenidium (Azygobranchiatc). 



Fam. 4. Trochidae. Visceral sac and shell coiled in a spiral ; eyes open ; 

 operculum horny ; with head-lobes between the tentacles. Troclius L. ; Marga- 

 rita Leach (Fig. 312) ; Monodonta Lam. 



Fam. 5. Stomatiidae. Spire of visceral sac and shell reduced. Stomatella 

 Lam. ; Gena Gray ; Broderipia Gray ; StoHiatia Lam. , without operculum ; 

 Phaneta Ad., fluviatile. 



Fam. 6. Delphinulidae. Visceral mass and shell spiral ; no cephalic lobes. 

 DelpMnula Lam. ; Cyclostrema 

 Marryat. 



Fam. 7. 

 Gray. 



Fam. 8. Turbinidae. Visceral 

 sac and shell spirally coiled ; 

 epipodial tentacles ; calcareous 

 operculum. Turbo L., top-shell. 

 PJiasianella Lam., pheasant-shell ; 

 Mollcria Jeffreys. 



Fam. 9. Neritopsidae. Neri- 

 topsis Grateloup. 



Fam. 10. Macluritidae. Ma- 

 clurea Lesueur. 



Fam. 11. Neritidae. Epipo- 

 dium little developed, without 

 tentacles ; a cephalic penis ; cal- 

 careous operculum ; eyes stalked. 

 Nerita L. ; Neritina Lam. , chiefly brackish water and fluviatile ; land species 

 are known ; N. fiumatilis Miiller, British rivers. Theodoxia Mont. ; Smaraydia- 

 Issel ; Septaria Fer. 



Fam. 12. Titiscanidae. Shell and operculum absent. Titiscania Bergh ; 

 T. limacina Bergh., Pacific Ocean. 



Fam. 13. Helicinidae. Epipodium without tentacles ; branchia absent, 

 mantle cavity transformed into a pulmonary chamber ; heart with a single 

 auricle, not traversed by the rectum. Operculum without apophysis. Terrestrial. 

 Helicina Lam., Central America and Bahamas ; Hydrocena Parreys ; Georissa 

 Blanford. 



Fam. 14. Proserpinidae. Branchia replaced by pulmonary cavity; mantle 

 partly reflected over shell; operculum absent. Terrestrial. Proserpina Gray, 

 Cuba, Jamaica, Venezuela ; Ceres Gray, Mexico. 



Sub-order 2. Pectinibranchiata (Ctenobranchia, Monotocardia). 



Ctenidium monopedinate, generally without labial commissure. 



The nerve-collar is behind the buccal mass, and there is no labial 

 commissure (except in Paludina and Ampullaria). The single 

 osphraclimn is often pectinate, and well differentiated. The eye is 

 always closed. Otocysts with otolith (except Palwlina, Vah'ata, 



Z 3 



FIG. 312. Marfja rita greenlandica (after Pelseneer, 

 ' from Lang). 1 head ; 2 anterior epipodal lobes ; 

 3 foot ; U pigmented eminences at the base of tin- 

 epipodial tentacles 5; 6 visceral sac. 



