MUSEUM OF COMPARATIVE ZOOLOGY. 27 



REPORT ON THE DEPARTMENT OF VERTEBRATE 



PALEONTOLOGY. 



By Charles R. Eastman. 



Field-work in the Colorado and Wyoming collecting regions 

 was resumed by the Assistant during the summer of 1901, with 

 the twofold object of making additions to the Museum collections, 

 and of studying the physical and stratigraphic relations of the 

 Green River and other well-known fossiliferous horizons. A 

 large number of exposures were visited with a view to determining 

 whether the beds in question were of lacustrine origin, as has 

 been commonly assumed, or of fluviatile, as recently suggested by 

 Professor Davis. In so far as the Green River shales are con- 

 cerned, the evidence seems to point conclusively in favor of 

 Hayden's original hypothesis that they were deposited at the 

 bottom of former lake basins ; but with regard to the Jurassic 

 Dinosaur bone-beds, there are various reasons for supposing many 

 of them to have been formed under fluviatile conditions. 



A number of valuable fresh-water fishes were obtained from 

 the Middle Eocene of Uinta County, Wyoming, and a quantity of 

 the usual type of Trenton and Jurassic fish-remains were collected 

 near Canon City, Colorado. An excellent opportunity for ac- 

 quiring a knowledge of local stratigraphy was afforded by partici- 

 pating in the ten days' excursion through Colorado which was 

 conducted by Professors Emmons and Van Hise immediately pre- 

 ceding the Denver meeting of the Geological Society of America. 

 Some time was spent by the Assistant in examining the principal 

 western collections of fossil vertebrates both last year and during 

 the present summer, particular attention being given to the type 

 specimens described by Newberry and Worthen and by St. John 

 and Worthen in the "Palaeontology of Illinois." The results of a 

 reinvestigation of some of these historic specimens are included 

 in a forthcoming number of the Museum " Bulletin." 



