104 IOWA ACADEMY OF SCIENCES. 



Now, the " closet-naturalist" has done abundant harm in this 

 as in other branches of science. Too remote, often, from the 

 phenomena under discussion, or too dainty to soil his fingers 

 with the toil and the exposure of field-work, he has passed 

 judgment upon the habits of forms which he knew only from 

 material submitted by mail; or still worse, he has taken 

 the work of others and,not appreciating the significance of the 

 facts so borrowed, has distorted them to do menial service 

 in the encouragement of some pet notion. 



In the particular case in hand, no distinction has been made 

 between the habits of the "depauperate" varieties and the 

 larger types of the same species, and too often the habits of one 

 species have been confused with those of another, of the same 

 genus, or even family, — a mistake most frequently made with 

 the Succineas. Again, the universality of certain species, — 

 their adaptability to varying conditions, — has been overlooked. 

 Zonitokles )iiinusci(h(s, Bifidaria peModon, B. contracta, Succlnen 

 avara, S. obUqua, etc., frequently occur in low places, — and then 

 often in great numbers, — but they are also found scattered over 

 comparatively dry hillsides at considerable altitudes, — and 

 some of these species in such places develop the "depauper- 

 ate " type, — that is, they average smaller in size. 



To show the preponderance of strictly terrestrial forms in 

 the loess, the writer calls attention to the fact that in the 

 collections made last June, at Natchez and Vicksburg, Miss., 

 and numbering over thirty species and nearly 4,000 specimens, 

 there is not a single aquatic form. And, furthermore, every 

 species which was collected in the loess of that region has been 

 found, by the writer, living upon the high bluffs and hills in 

 and near Natchez, or upon hillsides at considerable elevations 

 in other parts of the south, notably in northern Alabama, 

 Georgia, and Tennessee.* At Natches, the most common living 

 species is Succmea grosvenorii, and this crept upon the bare 

 surfaces of the loess clay which, at the time of the writer's 

 visit, had been baked by the hot summer sun of the south, 

 during a period of drouth lasting more than six weeks. More- 

 over, several scores of specimens which had been carried about 

 in the sun all day long in a box containing loess dust, and hence 



*It Is also a sigQifieaat fact that of all the living species found on the hills and 

 bluffs of Natchez, only two Leuchochila fallax and Pnlygura te.rana were found in the 

 loess of the region, only a single specimen of the first and two of the second were not 

 collected in the loess of that region. The former is not uncommon in the loess of the 

 north, while the latter is not known from the loess, at least to the writer. 



