2 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. I3I 



G. F. Sternberg, Franklin Pearce, and myself. The result of these 

 early searches was the nine specimens described in the preliminary 

 note of 1942. Smithsonian Institution parties revisited the localities 

 in 1948, 1949, 1951, 1953, and 1954. On most of these expeditions 

 I was assisted by the chief of our laboratory of vertebrate paleon- 

 tology, Franklin L. Pearce. In 1948, I was aided by my wife, Elisa- 

 beth, and son, Chester. Chester Gazin also assisted Pearce and me 

 in 1949. 



The excellent pencil drawings of specimens shown in the two plates 

 accompanying this report were made by Lawrence B. Isham, scien- 

 tific illustrator for the Department of Geology in the National 

 Museum. 



GEOLOGIC RELATIONS AND OCCURRENCE OF REMAINS 



Although the fossil-bearing beds on La Barge Creek have been 

 mapped by A. R. Schultz (1914) as Almy, and are so regarded by 

 Rubey ^ in his recent investigations of the region, it should be noted 

 that the type section for the Almy formation, in the vicinity of Evans- 

 ton, Wyo., is in a separate, although adjacent, basin of Tertiary dep- 

 osition and there may have been no actual continuity between the 

 two lithologically somewhat similar deposits. 



The Almy formation is mapped in the Upper Green River Basin 

 as a nearly continuous band along the east flank of the Wyoming 

 Range from the vicinity of La Barge Creek to Fall River in the 

 Hoback Basin. At La Barge Creek it appears and is shown by 

 Schultz to be in depositional contact with lower Paleozoic rocks to 

 the east and with upper Paleozoic and Triassic rocks forming the 

 front of the range to the west. The Almy area immediately to the 

 north of La Barge Creek is separated from the Eocene of the Green 

 River Basin on the east by faulting, shown as a thrust by Schultz in 

 which the lower Paleozoic beds underlying the Almy have ridden out 

 over the younger rocks to the east. To the south of La Barge Creek 

 the Paleozoic rocks which make up La Barge or Hogsback Ridge, 

 together with the trace of the thrust fault, disappear beneath the 

 Eocene of the Green River Basin, with the Knight formation extend- 

 ing westward to contact with the Almy, as it does again some distance 

 to the north. 



In the vicinity of the fossil occurrences the Almy beds are a red- 

 dish, pebbly clay, partly conglomeratic, dipping steeply to the south- 

 west toward La Barge Creek. They appear to be nearly conformable 



1 Oral communication. 



