VERTEBRATA OF THE TERTIARY, 



^^ 



T1m» PiitTco marls liavt- tlii-ir jiriiK-ipal devtloitnieut at this locality. I exam- 

 ined them throughout the forty miles of outcrop which I observed for fossil re- 

 mains, but succeeded in finding nothing but fossil wood. This is abundant in the 



region of the Galliuas, and includes silicilied fiagments 

 of dicotyledonous and palm trees. On the Puerco, 

 portions of trunks and limbs are strewn on the hills 

 and ravines; in some localities the mass of fragments 

 indicating the place where some large tree had broken 

 up. At one point east of the river I found the stump 

 of a dicotyledonous tree which measured 5 feet in 

 ^ I > diameter. 



The fauna of this formation is diftereut from 



that of the other Eocenes in the presence of a 



saurian. Cha»ip80saun(.s. which is characteristic of the 



Laramie Cretaceous, and of marsupial Mammals {Ptilo- 



^ ^ '^ 'liii and Catnjmilis) which are remnants of a type 



= -■ -fi known otherwise from the Jurassic. Characteristic 



x i -^ genera are Catathlceus, a many-toed omnivore, FnU- 



Z t = tacotherinm, a gnawing TiUodont, and various flesh- 



= ■? s eaters with primitive teeth. Coryphodon is, so far, 



" o ^ unknown. 



3 '•^' a 



t K 





o 1:2 



THE WASATCH. 



2 3D o The Wasatch Group is the lowest of a series of 



"o v. I these fresh-water Tertiaiy groups, all of which are inti- 

 c B"? mately connected, not only by an evident continuity of 

 > >• o sedimentation throughout, but also by the passage of a 

 "I •= H portion of the molluscan species from one group up into 

 2 ;^ I the next above. Not only were those three groups, 

 = f i. aggregating more than a mile in thickness, evidently 

 to £ ^ produced by uninterrupted sedimentation, but it seems 

 ^ .| i e()ually evident that it was likewise uninterrui»ted lie- 

 § I T tween the Laramie and Wasatch epochs, although there 

 f J f was then a change from brackish to fresh waters, and 

 "^ ^f a consetpient change of all the species of invertebrates 



1 - J then inhabiting those waters. 

 "■ I e In his annual rejtort for 1870, Dr. Ilayden pro- 



2 S. posed the name *' Wasatch Group " for a series of strata 

 " ''" that are extensively developed in Southern Wyoming 



J and adjacent parts of Utah and Colorado. I regard 

 s the series of strata to which Mr. King lias given the 

 ^ name "Vermilion Creek Group," and Professor Powell 

 _■ that of "Bitter Creek Grouj)," as geologically equiva- 

 lent with the Wasatch Grf)ui) of Dr. Ilayden, and 1 therefore use that name iu this 

 report in accordance with tlie recognized rule iu such cases. 



