THE NAUTILUS. 105 
where the water disappeared, was a series of clear, rather deep 
pools, called ‘‘ water holes,’’ connected by a tiny, clear rivulet. 
In one of these pools was collected that year the type lot of 
Sphaeriwm hendersoni Sterki. Then came the ‘‘boom”’ in dry 
lands in Eastern Colorado. Scores of small tracts of prairie 
sod, many of them on steep slopes, were broken by the settler’s 
plow. The dry soil, no longer held together by the sod, was 
carried into the valley by summer storms, filling many of the 
pools and depositing a thick coat of mud over the whole stream 
bed. In June, 1912, I revisited the locality, and found no 
clear water at all, and not a single mollusk of any species. The 
sluggish stream carried a heavy load of silt so fine it would not 
settle. Probably the Sphaerium is extinct at the type locality. 
It is likely that innumerable changes in the faunas of the 
West are occurring as a result of the settlement of the country 
and consequent changes in environment. This is known to be 
true of birds and mammals. For this reason it is desirable that 
biological work in this vast region be pushed as rapidly as pos- 
sible, to provide data for future estimates of biological changes. 
NOTES. 
Hopeson Couttection. I have just secured the collection of 
the late Chas. 8. Hodgson, containing some 2500 to 3000 
species, a few fossils and books. Besides his work in Illinois 
he did considerable collecting in other places and added to the 
collection by exchange and purchase.— A. A. HINKLEY. 
Dr. G. Datitas Hanna, who for eight years has been an 
assistant in the United States Bureau of Fisheries, has been ap- 
pointed curator of invertebrate paleontology in the California 
Academy of Sciences. Dr. Hanna has for seven seasons been 
engaged in scientific work on the Pribilof Islands, Alaska, hav- 
ing taken the census of the fur seal herd for five consecutive 
years. He brings to the museum of the Academy his collection 
of mollusks which numbers about 100,000 specimens. 
FLUKE In Puitomycus. It may be of interest to the readers 
