352 
On thè genus Pomphólyx and its Allies, 
Sub-genus Bathyoingjhalus. Agassiz. 1837. 
Shell depresseci, many whorled, periplieiy simple. 
Type Bathyomphalus contortus = PlanorMs coìitortus. Limi. 
Sub-genus Aìiisus. Fitz. 1833. 
Shell greatly depressed, whorls verj numerous, keeled. 
Tjpe Anisus vortex = Planorhis vortex. Limi. 
Genus Segmentina. Flem. 1828. 
Shell furnished with internai transverse laininse or teetli ; de- 
pressed. 
Sub-genus Planorhxda. Hald. ISll. 
LaminfB, except thè last, absorbed in thè àdult. 
Type Planorbula armigera — Planorbis armigerus. Say. 
Sub-genus Segmentina. Fieni. 1828. 
Lamlnfe persistent. 
Type Segmentina lacustris — Planorhis lacustris, Lightfoot. 
(?) Sub-family Camptoceeix^. Dall. 
Jaws ? 
Shell sinistrai. Foot short. Tentacles cylindrical, obtuse. 
Mantle not passing bej'^ond thè shell.. Teeth ? 
Genus Camptoceras. Bens. 1831.* 
Shell Avitli thè whorls dìsunited, siib-angulate. Aperture en- 
tire, produced and reflexed anteriorly. 
Type Camptoceras terébra. Benson. 
Sub-family Pompholigest^. Dall. 
(= PoMPHOLiNiE. Dall, 1866. olim.) 
Buccal piate subcordiforni. Laterals absent. Genitalia on thè 
left side. Shell dextral, depressed, few-whoided. 
* This genus may eventually prove to be more closely conuected witb Fom- 
lìholyx is evident from our present knowledge of it. 
