»5c ShUnek on the fossils of the Loess at Iowa C'Uy^ la. 
xliameter 31^ mm. This is soniewhat greater than in our recent 
forms. 
6. Patulasirig-osa {^(jowld.) Binn, The variety known as/*. 
€ooperi occurs in one of our exposures. The species is extinct in 
thi.s locality. 
7. Patula striatella {^A.\\\.\\.) Morse. This is one of the most 
common species of the Loess. The average measurement of the 
fossils is about equal to that of the recent specimens. The fossil 
•t'ggs of this species arc frequently found. 
8. JFIellcodlscus Uneatus [Sixy.) Morse. But four specimens 
>vere foinid, which do not differ from the average recent forms. 
c). Ferussacia subcylindrica (L.) Binn. Five fossils were 
found which arc in all respects like the only tvv o recent speci- 
mens which were collected here. 
10. Pupa arinljcra Say. But few specimens occur, and 
these are scarcely distinguishable from recent specimens, ex- 
cept by the unmistakable bleached character so peculiar to Loess 
fossils. 
11. Pupa muscoriivi L. Rather common. Now extinct 
in this locality. 
12. Pupa 3/rt«(// (Morse) Binn. Many hundred specimens 
were taken. The recent form is not found here. 
13. Vertigo simplex (fjowMS.^ Stimp. Several hundred spec- 
i^icns which have been referred rather doubtfully to this species, 
were taken. The species is now extinct in this locality, but the 
dimensions of recent types are given as: length, i-^^ mm., diam., 
g^ mm., and the number of whorls as five; whereas the best 
specimens of our fossil form measure 31^ mm. in length and "^ 
mm. in diameter, and the number of whorls is seven. In all 
respects, excepting length and number of whorls, our specimens 
are certainly V. simplex., though a number of conchologists 
have returned them to me as Pupa muscoru7n L.! P. mus- 
corutn has twice the diaineter of this Vertigo., and its aperture 
with the slightly expanded lip differs very much from that of 
the Vertigo., which is regularly rounded, with a simple lip. 
14. Mcsodon m^iiltilincata (Say) Try. The fossils are of f re- 
fluent occurence, but they are much smaller than our recent 
specimens. The smallest fossil specimen which was found 
measures 121^ mm. in greater diameter, atjd the largest 16 mm., 
