78 ANNUAL REPORT SMITHSONIAN INSTITUTION, 1949 
will be inundated when the reservoir is flooded, were found. The 
results of the work there confirmed the conclusions of the members of 
the United States Geological Survey who had mapped the structure 
and stratigraphy of that area. 
From July 14 to August 19 the Oligocene and Miocene deposits in 
the Canyon Ferry Reservoir area on the Missouri River north of 
Townsend, Broadwater County, Mont., were prospected for fossils. 
Material was obtained from three localities in the Oligocene and two 
in the Miocene. All those localities will be inundated. 
After the close of the work at Canyon Ferry, White’s party pro- 
ceeded to the Angostura Reservoir on the Cheyenne River in Fall 
River County, S. Dak., to make a physiographic study of the area in 
connection with an early-man site. The period from August 21 to 
September 3 was spent in collecting data for that study. The party 
returned to Lincoln, Nebr., on September 4 in order to prepare a 
preliminary report on the results of the physiographic study. 
From September 23 to October 1 the Upper Cretaceous Carlile 
Shale in Cedar Bluff Reservoir on the Smoky Hill River south of 
Wakeeney, Trego County, Kans., was prospected for vertebrate fossils. 
Although a number of specimens were found, they were so badly 
disintegrated by the crystallization of gypsum and the weathering of 
marcasite that they were not worth collecting. 
About 70 specimens, representing 20 genera, were obtained in the 
Boysen Reservoir area. Although the specimens were for the most 
part rather fragmentary, they were sufficiently well preserved to estab- 
lish the age of those beds as belonging to the Lost Cabin faunal zone 
of the lower Eocene, a fact that had not previously been demonstrated. 
In the material obtained is the most nearly complete skull yet found of 
the primitive insectivore, Didelphodus. Although badly crushed and 
not impressive to look at, it adds a number of previously unknown 
details to the knowledge of the cranial morphology of that form. 
Also the skull and jaws of Didymictis, a primitive carnivore a little 
larger than a fox, was obtained in that area. Heretofore the form was 
known only from upper and lower dentitions. 
Nearly 125 specimens, principally insectivores, rodents, and small 
artiodactyls, were obtained in the Canyon Ferry Reservoir area. 
Most of the specimens were found in the Oligocene deposits which 
previously were very poorly known. ‘The material obtained demon- 
strated that deposits of both lower and middle Oligocene age were 
present in that area. One of the Oligocene insectivores belongs to a 
problematical family previously unknown in deposits later than the 
upper Eocene. Also, it is the best-preserved specimen yet found and 
adds many details of the skull and dentition to the knowledge of that 
group. The small Oligocene mammals of that area, when compared 
