224 AMERICAN JOURNAL 



Sub-order Limnophila. 



Amphibious and fluviatile species. Head furnished with 

 two tentacular, with eyes at their bases. 



A few of these shells are considered terrestrial, because they 

 inhabit land within reach of the tides. 



§ Shell oval-oblong or conoidal, mouth dentate within. 

 Not umbilicaie. 



Family Auriculidje. 



The American are all sea-shore species, except one minute 

 shell {Carychium exiguum) which extends far inland, upon 

 river margins and in damp places. 



Section B.— PHANEROPNEUMONA (Operculata). 



Shell operculate. Head furnished with two tentacular, with 

 eyes sessile at their bases. Eespiratory orifice without a valve. 



Sub-order Ectopathalma. 



Eyes lateral, at the external bases of the tentacles. Oper- 

 culum spiral or concentric. 



§ Shell orbicular or turbinate, whorls convex, lip con- 

 tinuous, reflected, umbilicus open or indented. 



Family Cyclophorid^. 



A few species inhabit the Gulf States. 



§§ Shell depressed, conical, whorls but Utile convex, lip 

 not continuous, reflected, umbilicus covered by a heavy 

 deposit of callus. 



Family HELiciNiDiE. 



Tropical. Several species in the Gulf States, and one found 

 as far north as Indiana. None in California. 



Sub-order Opisopthalma. 



Eyes placed posterior to the bases of the tentacles. Oper- 

 culum sub-spiral. 



§ Shell cylindrical, apex truncate. 



Family Truncatellid^e. 



Inhabiting sea-shores of Florida and California. 



