PHYSA. 125 
Genus PH YS A, Draparnaud. 
For description of the soft parts, see Halde- 
man’s Monograph, p. 20. Prof. Haldeman 
was not aware that Ph. hypnorwm differs from 
the other species in the mantle margin being 
without digitations, hence his remark that 
“ The animal is distinguished from Limnea by 
the digitated mantle,” etc., must be under- 
stood to apply to the genus Physa as restricted 
by subsequent authors. 
The argument of Prof. H. (p. 22) in favor 
of retaining Physa instead of the older name 
Bulinus on the score of expediency would find 
no favor at the present day, and the latter 
name would have been adopted long since had 
it not been discovered that the animal, instead 
of being the same, is generically distinct. 
The following subgenera of Physa are ad- 
mitted,—none of them containing many spe- 
cies : 
(41) 
