^16 [Sept. 21, 



■PALEONTOLOGICAL BULLETIN, 



No. 37. 



From Prof. B. D. Cope, a letter to the Secretary, dated Sully- 

 Springs, Dakota, Sept. 7, 1883, was read, as follows : 



On a New Basin of White River Age in Dakota. 



"I have the pleasure to announce to you that I have within the past 

 week discovered the locality of a new lake of the White River epoch, at a 

 point in this Territory nearly 200 miles north-west of the nearest boundary 

 of the deposit of this age hitherto known. The beds, which are unmis- 

 takably of the White River formation, consist of greenish sandstone, and 

 sand-beds, of a combined thickness of about 100 feet- These rest on white 

 calcareous clay, rocks and marls, of a total thickness of 100 feet. These 

 probably also belong to the White River epoch, but contain no fossils. Be. 

 low this deposit is a third bed of drab clay, which swells and cracks on 

 exposure to weather, which rests on a thick bed of white and gray sand, 

 more or less mixed with gravel. This bed, with the overlying clay, proba- 

 bly belongs to the Laramie period, as the beds lower in the series certainly 

 do. 



" The deposit as observed, does not extend over ten miles in north and 

 south diameter. The east and west extent was not determined, but is 

 much greater, 



"The fossils, which indicate clearly the age of the formation, are the 

 following : 



Pisces. 



Rhineastes,' sp. nov i 



Amiurus, sp. nov / 



