353 On the genus Pompholyx and its Allies, 



Sub-genus Bathyomphaiua. Agassiz. 1837. 



Shell depressed, many whorled, periphery simple. 



Type Bothyomphobus oontortus = Planorbis aontortus. Linn. 



Sub-genus Anisus. Fitz. 1833. 

 Shell greatly depressed, whorls very numerous, keeled. 

 Type Anisus vortex = Planorbis vortex. Linn. 



Genus Seg?ne?ithia. Fleni. 1828. 

 Shell furnished with internal transverse lamina; or teeth ; de- 

 pressed. 



Sub-genus Planorbtda. Ilald. 1^44. 



Laminae, except the last, absorbed in the adult. 



Type Planorbvla wnrwgera— Planorbis armigerus. Say. 



Sub-genus Segmentma. Flein. 1828. 



Lam hue persistent. 



Type Segmentvna laeustris = Planorbis laeustris. Lightfoot. 



('.) Sub-family Camptockkix.e. Dall. 

 Jaw- '. 



Shell sinistral. Foot short. Tentacles cylindrical, obtuse. 

 Mantle oot passing beyond the shell. Teeth ? 



Genus Camptooeras. liens. 1834.* 

 Shell with the whorls disunited, sub-ungulate. Aperture en- 

 tire, produced and rctiexed anteriorly. 

 Type Camptooeras terebra. Benson. 



Subfamily PompHoi.njin.k. Dall. 



(= Pomphouna. Dall, 1866. olim.) 



Buccal plate BUbcordiform. Laterals absent. Genitalia on the 



left Bide. Shell dextral, depressed, fewwhorled. 



• Tin.-. gttaUM limy . v. ntunlly prove to be more cloHely connected with I'mii- 

 fX than ih rvidmt from our present knowledge of it. 



