250 
IOWA ACADEMY OF SCIENCE 
In connection with his discussion of the above-noted deposits, 
Professor Todd calls upon the advocates of the aeolian hypothesis 
to show cause for claiming that most of the Missouri River loess 
is of aerial deposition when so many similar deposits are unques- 
tionably of aqueous origin.” Before entering upon this task the 
writer calls upon him to designate exactly where these “similar 
deposits” are located, — not by reference to books and papers, but 
to exact localities where they may be studied in the field. The 
cases which he has thus far cited certainly do not give grounds 
for his challenge. 
In closing, the writer desires to call attention to one more state- 
ment made by Professor Todd which is misleading. He states that 
the writer “postulates timber-clad hills for the habitat of his land 
shells.” In various papers on the subject the writer has referred 
to the fact that land-snails are most abundant in timber covered 
areas, but they are not absolutely restricted to them. Other vege- 
tation may furnish food and shelter for some of the species. 
Nevertheless, if we are to judge of ’the past from the present the 
great majority of the fossils once lived upon areas covered with 
trees or shrubs. 
But in that case, he asks, “how can the absence of large root 
marks be accounted for?” During the spring the writer made an 
investigation of the loess ridge in which certain human remains 
were found near Florence, Neb. In the course of this work he 
had occasion to re-excavate and slightly extend the excavation 
made by Professor Barbour and Mr. Gilder. The section showed 
cavities near the surface, left by several large roots, and in the 
cavities there remained only ^slight traces of vegetable matter in 
the form of a brown residue of the consistency of fine sawdust. 
The walls of the cavity were in many places without discoloration 
by organic matter, and in wet seasons such cavities would be easily 
filled by loess without leaving any trace of the root. The same 
thing takes place with smaller roots in many loess exposures. 
This decay and disappearance of roots is taking place now, and 
has undoubtedly continued through long periods of time in which 
the loess accumulated. 
But if Professor Todd finds difficulty in explaining what be- 
comes of the roots in a gradually increasing loess deposit, will he 
kindly explain what has become of the roots of the countless gen- 
erations of plants which have undoubtedly developed upon the loess 
deposits which he assumes to be practically without increment? 
The upper portions of the loess subsoils ought in that case to be 
