POST-GLACIAL MOLLUSCA 669 
a longer spire and deeper sutures. There are seven full whorls 
in the largest fossil specimen, which measures as follows: Length, 
40; breadth, 22; aperture length, 20; breadth, 12 mm. 
Integra is widely distributed in Illinois but has been confounded 
with subsolida and decisa, from both of which it differs notably. 
VALVATIDAE 
Valvata bicarinata Lea 
Not common. 
AMNICOLIDAE 
Amnicola limosa (Say) 
Two shells of this species were observed in the loose sand taken 
from the aperture of Ambloxis. 
PLEUROCERIDAE 
Pleurocera elevatum (Say) 
As in the deposit examined by Dr. Savage, this species is the 
dominant mollusk in the deposits examined by the writer, and the 
shells exhibit the same range of variation as do those from the lower 
stratum. Several individuals are smooth without indication oi 
spiral liration and every degree of ornamentation is represented to 
shells with a heavy, keel-like carina on the periphery. This 
species is abundant, living in the Sangamon River, where it is 
equally variable. 
PLANORBIDAE 
Planorbis antrosus Conrad 
Rather common, but the individuals are smaller than normal. 
Planorbis campanulatus Say 
One adult shell of this species was found in the collection. 
ENDODONTIDAE 
Pyramidula alternata (Say) 
Several shells of this common land mollusk were collected from 
the deposit, indicating that this wood snail has lived in this vicinity 
for along time. It was not found in the lower deposit but a related 
species, Pyramidula solitaria, occurred. 
