l8 SMITHSONIAN INSTITUTION 



the western side of the basin, especially on Dorsey Creek. For lack 

 of time no collecting was done in the upper beds. 



In the time spent here we were successful in obtaining some few 

 specimens of outstanding interest and a great mass of scientifically 

 important material. Worthy of especial mention are the following : A 

 considerable part of the skeleton of a large creodont, Pachyaena, a 

 large carnivorous mammal ; three partial skeletons of Coryphodon, a 

 rhinoceroslike animal (fig. 15) ; a skull and lower jaws of the dawn 

 horse Eohippus; a skull and lower jaws of a rare edentate ; lizard 

 remains ; and six more or less complete crocodile skulls of the genus 

 Allogonathosuchus. In addition there were found fragmentary parts 

 of no less than five individuals of Diatryma, the giant nonflying bird 

 of this period. Since it reached a height of nearly 7 feet, the large 

 size of its bones probably accounts for the considerable numbers of 

 individuals that have been found, as bird remains are among the 

 rarest of fossils. In this connection, William Stein brought to my 

 attention the interesting fact that all of the known Diatryma remains 

 found in the Wasatch formation of the Big Horn Basin, including 

 a nearly perfect skeleton discovered by him, have come from a nar- 

 row strip of country on the eastern side, not more than 2 miles wide 

 and 4 or 5 miles long. 



During the entire field season good weather prevailed, except for 

 the extreme heat, and only two days were lost on account of rain. 

 Although we were not fortunate enough to find a paleontological 

 prize, such as a complete skeleton, the collections made are of the 

 utmost importance from the fact that practically all of the specimens 

 secured are new to our collection and thus fill gaps existent since the 

 establishment of the division of vertebrate paleontology in the Na- 

 tional Museum. From a scientific point of view, the small mam- 

 malian material — tooth-filled jaws and parts of skulls, some of them 

 associated with skeletal material — forms the most important part of 

 the year's collections. In all there are more than 600 such specimens, 

 which, although containing some duplicates, give to the division an 

 adequate working series of this basic fauna. It is anticipated that 

 many new forms of animal life will be revealed when a systematic 

 study is made. 



