WEST AMERICAN SHELLS 
P. trwolvis, Say, U.S. N. M. XIV, p. 102. 
var. horm, Tryon, Nautilus XIII, p. 65; 
XVII, p. 84. 
var. binneyi, Tryon, Nautilus IX, p. 102. 
P. tumens, Cpr., U. 8. N. M. XIV, p. 102. 
P. parvus, Say, Nautilus XIII, p. 65; X VII, 
p. 84. 
P. hebmannu, Dunker, U. 8S. N. M. XIX, p. 
369. 
P. tuwmidus, Pfeiffer, U. S. N. M. XIX, p. 
369. 
P. subcrenatus, Cpr., S. I. Mis. Coll. 148, 
Toy LWUBY 
P. vermicularis, Gould, Nautilus IX, p. 102; 
Arnold, p. 195. 
var. disjectus, J. G. Cooper, Nautilus IV, 
ps dials 
P. centervillensis, Tryon, Nautilus IX, p. 
36. 
P. callioglyptus, Vanetta, Nautilus IX, p. 
102; TX, p. 54. 
P. ammon, Gould, Nautilus V, p. 56; XIII, 
Os koulla 
P. opercularis, Gould, Nautilus V, p. 56. 
var. multilineatus, Van., Nautilus XIII, p. 
48, 
Genus, Helisoma, Swainson 
H. bicarinatus, Say, 8. I. Miss. Coll. 143, p. 
1a 
Genus, Ancylus, Geoff 
A. fragilis, Tryon, Nautilus V, p. 56; IX, p. 
OZ? 
