Gasteropodous MoUusca into larger Groups and Families. 131 



panded, covering the shell ; outer lateral teeth conical, entire or 

 toothed. Cyprcea, Trivia, t Erato. 



Fam. 24. Pediculariad^. Operculum none; mantle en- 

 closed. Pedicularia. 



Fam. 25. ApoRRHAiDiE. Operculum annular, ovate, nucleus 

 apical, small; mantle, outer edge expanded, lobed, or rarely re- 

 flexed ; siphon and canal of shell bent to the right. Aporrhais ; 

 Trichotropis, lingual membrane short, broad ; ? Struthiolaria. 



(See observations on Trichotropis at p. 129.) 



** Eyes on elongated peduncles. 



Fam. 26. Strombid.e. Foot compressed, used for jumping, 

 not walking ; mantle, outer side generally expanded and often 

 lobed ; muzzle longly conical. 



a. Strombina. Tentacles on middle of eye-pedicel ; operculum 

 claw-like. Strombus, Pterocera, Fusus. 



b. Serapliina. Tentacles none ?, operculum none. Seraphys. 



B. Operculum subannular ; mantle and shell simple in front; 

 eyes sessile. 



Fam. 27. Phorid^. Foot compressed, used for jumping, not 

 walking ; eyes sessile, on the outer side of the subulate tentacles ; 

 operculum large, horny, subannular; muzzle conical, produced; 

 tongue ■ ? ; teeth ? Phorus, Onustus. 



C. Operculum annular, regular ; mantle with a siphon in front ; ^ 

 shell simple in front ; eyes produced near the outer side of the base /.iJ?^ i>«aaaA^ 

 of the subulate tentacles. 



Fam. 28. Ampullariad^. Central teeth acute, lateral, sub- 

 ulate. Ampullaria, Marissa, Pomus, Pomella, Lanistes, Asolene. 



D. Operculumannular,regular; mantle and shell simple in front; 

 eyes sessile, on the outeft- side of the base of the subulate tentacles. 



Fam. 29. Viviparid^e. Teeth abnormal, laminar, longitu- 

 dinal, ovate ; apex recurved, toothed on each side the tip ; inner 

 lateral tooth bi'oad. Viviparus, Paludomus, Bithinia. 



E. Operculum annular, regular, ivith an internal process ; mantle 

 and shell simple in front ; eyes sessile, far back behind the tentacles. 



Fam. 30. Rissoellid^. Rostrum divided into two tentacular 

 lobes in front ; " teeth in five series," Alder. Rissoella = Jef- \ 

 freysia, Alder; Rissoina. 



9* 



