Shimek on the fossils of the Loess at Iowa City, la . 15* 
whereas recent specimens from this locality vary from 32 ram. 
to 26 mm. I have, however, collected I'ecent specimens in Har- 
din county, the smallest of which equals the largest fossils, i. c 
16 mm. in greater diameter. 
15. Vallonia pulchclla {yiweW^ ^inn. The fossils are quite 
abundant. Their average greater diameter is three mm. TJie 
recent forms average only two and a half mm. 
16. Succinea avara Say. The form which has been re- 
ferred to this species (^curs in great abundance in our Loess.. 
It certainly is not typical 6". avara^ but coincides more nearly 
with Binney's description and figure of J>. verilli Bland, a 
boreal species. Our specimens average a trifle more than seven 
mm. in length. Our low-land form of living 6". avara is very 
much larger and has a proportionally larger body-whorl, while 
the form which lives in dry rocky places is more corpulent. 
Both are unlike the fossil form. 
17. Succinea vermeta Say. A form identical with the 
large 6". avara known commonly as var. vermeta occurs in 
great abundance in our deposits. It seems to change how- 
ever so gradually into the narrow, depauperate forms of 
6". obliqua that in a set of several hundred specimens I find it 
impossible to satisfactorily separate the two forms. Many of 
the fossil specimens are identical in form and size with the re- 
cent ones, but the average is rather larger. 
18. Succinea obliqua Say. The fossils referable to this, 
species are somewhat smaller, narrower and have a more ele- 
vated spire than our local recent specimens. 
19. I^imncea caperata Say. Common. The fossils are 
smaller than our recent local form, but are equal to specimens 
from Marshall county, Iowa. 
20. Linincea huniilis Say. Two forms of this variable 
species occur locally in considerable abundance. The broader 
form with longer aperture and shorter spire finds its exact 
counterpart in our local living form, but the other does not oc- 
cur here now. 
The latter form has been erroneously called L. desidiosa. U 
may prove to be distinct. 
21. Limncea desidiosa Say. Specimens which may be 
referred to this species are occasionally found. They are mucii 
smaller than the recent local form. 
