Shimek on the fossils of ike Loess at Iowa Cily, la. 149 
NOTES ON THE FOSSILS OF THE LOESS AT 
IOWA CITY, IOWA. 
BY PROFESSOR B. SHIMEK. 
The typical Loess deposits of the vicinity of Iowa City con- 
tain an abundance of specimens of mollusk remains, the careful 
study of which will no doubt cast much new light on the evo- 
lution of some modern species, as well as on the climatic condi- 
tions under which these forms existed. 
In the following brief notes I will merely make a compari- 
son of our Loess fossils with the same species now living here,, 
as I desire to reserve the results of more extended observation* 
for a future paper. 
All of the species noted in the following list were collected 
by myself in the immediate vicinity of Iowa City, and the 
greatest care was exercised to admit no old, bleached recent 
shells as Loess fossils. The rarer species were all obtained hj 
digging in hitherto undisturbed Loess. 
1. Zonitcs arboreiis (Say.) Binn. Only three imperfect 
specimens very much like our recent forms were found. 
2. Zonltes viridi^ I us {Jslcn\s.G.^ Binn. Two fine specimentj- 
were taken which were rather smaller than average recent ones. 
3. Zointes 7niniisculus (Binn.) Fisch. and Cr. Three fossil 
specimens were found. My largest recent specimen measures 
2j^ mm. in greater diameter, whereas the three fossils measure 
each three mm. 
4. Zonitcs Umatulns (Ward.) Binn. The fossil forms are of 
frequent occurrence. The sjDccies does not live here at present^ 
but our fossils are much larger than any recent specimens which 
have come to my notice. 
5. Zonitcs f7dvus{Y)x'A^.^V>\\\n. Abundant. Average greater 
1870, p. 59. But in a foot-note on same page he writes, "I propose the 
subgeneric name Vortifex for these shells, which differ from the typical 
forms of Can7iifcx." Attention was elsewhere called to the orthographj 
of the subgeneric name, which should have been Voriiafex. No diagno- 
sis of the subgenus was ever given, and the one herein offered is based 
on Meek's specific description of V. Binncyi, which he has designated n^ 
the typical species. 
