356 
On thè genus Pompholyx and its Allies, 
Sub-genus Isidora. Elir. 1831. 
Shell with thè whorls inflated, columella destitute of a fold, 
semi-urahilicated. 
Type Isidora contorta = Physa contorta. Mieli. 
Sub-genus Ameria. H. Adams. 1861. 
Spire short ; whorls appressed, flattened, tabulate or carinate 
posteriorly. Last whorl much thè largest. 
Example, Ameria scalar is = Paludina scalaris. Jay.* 
Tampa Bay, Eia. 
Sub-genus Physodon. Hald. 1853. 
Shell solid, smooth, columella toothed, outer lip thickened. 
Type Physodon microstoma. Hald. 
• Genus Macrojyhysa. Meek. 1865. 
Spire very much elongated, whorls numerous, nearly equal ; 
body whorl short ; aperture less than one-fourth thè length of 
thè slender, cylindriform shell ; apex obtuse. 
Type Macrophysa columnaris — Physa columnaris. Desìi. 
Tossii in thè Eocene of thè Paris Basiu. 
Genus Bulinus. Adans. 1757. {Ajdexa., Eleni.) 
‘Mantle edge simple. Buccal piate cartilaginoiis. Tentacles 
long, filiform. 
Shell sinistrai, elongate ; margin of aperture entire. 
Type Bulinits hypnorum. Linn. 
Genus Physopsis. Krauss. 1818. 
Shell ovate, thin ; outer lip acute, columella plicate, invo- 
lute. Soft parts unkiiown. 
Type Physopsis africana. Kranss. 
* A careful examination of a number of specimens of this singular form 
shows tbat it is distinct, and not a young PlanorMs, as bas been suspected. 
Most of tbe species of this group are from thè Southern Hemisphere. 
