44 THE CHICAGO ACADEMY OF SCIENCES. 
DESCRIPTION OF SPECIES. 
Note.—The writer has not been able to make a satisfactory key to the 
genera for the reason that a number are founded upon anatomical characters. 
KEY TO FAMILIES IN THIS REPORT. 
A. Shell bivalve. 
a. Shell large, pearly, lateral teeth placed posterior of car- 
GInAITEeth en pei yetler sas siefe cisic; Vela) ieip o.s acorsteaiseefemeterets Unionide 
b. Shell small, not pearly, lateral teeth placed both anterior 
and posterior of cardinalitecth (2.5. .25.0 9. ose Tee ee Sphertide 
B. Shell univalve. 4 
a. Inhabiting land and breathing air; tentacles invertible 
and eyes at their tips. 
1. Shell heliciform, smooth, shining. 
*Shell flat, concave, smooth and shining, but 
not vitreous, umbilicus very wide and deep 
ao ole Pip tatese See ere Wd’ aoe iw he le SR gM Circinariide 
**Shell flat to orbicular, smooth, shining and 
vitreous, umbilicus generally narrow........ Zonitide 
2. Shell heliciform, dull, generally coarsely ribbed. 
*Edge of aperture simple, sharp........... Endodontide 
**Edge of aperture reflected .2 2.2 Jc..c. sca Helicide 
3. Shells small, elongated aperture about one-third 
of length. 
*Apetture with teeth ior foldsy...3-.... -.s2se— Pupide 
<¥Anectnre withoutteeth’.\s0 515). 2a oleae Achatinide 
4. Shell large, oval, aperture two-thirds of length. . Succineide 
5. Animal without external shell. 
*Mantle covering only pulmonary cavity, shell 
INLEELT AY coi octes yp erate ee oie .al soot ees arene .....Limacide 
**Mantle covering entire body, no shell..... Philomycide 
6. Animal with small, ear shaped shell placed at 
the posterior end of the body............... Testacellide 
b. Inhabiting land; tentacles contractile, but not invertible; 
eyes placed at their bases, 
1. Shell small columella with a fold, and parietal 
wall with one or two denticles............... Auriculide 
c. Inhabiting fresh water, but coming to the surface for air, 
which is necessary for respiration. 
1. Shell dextral; in one genus patelliform.......... Limneide 
2. Shell senistval vos ea ce e's ».¥ (0:2 s:3» one Physide 
d. Inhabiting and breathing in fresh water; does not come 
to the surface for air. 
1. Shell large, spire very long and pointed; aper- 
ture about one-third of length ............. Pleuroceride 
tExcepting Pupa fallax, which has no teeth. 
