38 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. Ill 



light, Mission, Brenner, Canyon Ferry, Tiber, Ross, Hobson, and 

 Snowy appeared sufficiently promising to be recommended for further 

 attention. 



Tliis trip was interrupted between August 20 and September 11, 

 during which period Dr. White and his assistant excavated the skull 

 and other skeletal parts of a dinosaur at Middle Fork Reservoir in 

 Johnson County, Wyo. The dinosaur is from the Upper Jurassic 

 Morrison formation, and has been identified as Diplodocus. 



On October 7, Dr. White left Lincoln again to conduct intensive 

 survey and fossil-collecting at Boysen. Enroute he examined paleonto- 

 logical collections at the Zeitner Museum, Mission, S. Dak., and made 

 preHminary inspections of the proposed Philip and Rocky Ford 

 Reservoir areas, respectively located on Bad River in Haakon County, 

 S. Dak., and on the White River in Washington County, S. Dak. 



The field work at Boysen terminated on November 7. Most of the 

 collecting during this period was in the Eocene Wind River forma- 

 tion in the Cottonwood Creek drainage on the west side of Big Horn 

 River. Among the specimens obtained the following may be noted, 

 all represented by incomplete remains: a lemuroid (Pelycodus), a 

 primitive tapir (Heptodon), an extinct mammal (Coryphodon) , and 

 the carapace (pi. 6, fig. 2) of a soft-shelled turtle (Amyda). 



Prospects in this locality are believed to be very promising, and 

 plans are for further work next spring. This would involve a more 

 intensive reexamination of the Cottonwood Creek locale, as well as 

 investigation of other known fossil localities in the basin area. 



In summary, paleontological reconnaissance was carried out at 

 94 proposed reservoir areas between May 2 and November 7, 1947. 

 Twelve of these are in intrusive granite and contain nothing of interest 

 to paleontology. Seven are in geologic strata from which vertebrate 

 fossils are at present unknown. At 25, the reconnaissance showed 

 that fossil deposits will be directly affected and recommendations have 

 been made for further studies if and when construction work is initi- 

 ated. At the remaining areas, the vegetation cover precluded profit- 

 able search for fossils on the existing land surface, though the possi- 

 bility remains that construction activities may in some places uncover 

 worth-while materials. 



As might be expected, the preliminary nature of most of the pale- 

 ontological work to date has resulted in acquisition of relatively little 

 exhibit or study material. Outstanding finds have been noted else- 

 where in this report. A highly worth-while working knowledge of the 

 units visited, of their geologic setting, and their paleontologic potenti- 

 alities has been gained. It seems certain that intensification of this 



