242 DESCRIPTIVE GEOLOGY. 



Asineops squamifrons, Cope. 

 Asineops viridensis, Cope. 

 Erismatopterus Bichseckeri, Cope. 



INSECTS (COLEOPTEEA). 



AntJierophagus priscus, Scudder. 



Endiagogus saxdtilis, Scudder. 



Trypodendron impressus, Scudder. 



Corymbites velatus, Scudder. 

 The molluscan remains of this formation, however, found principally 

 near the base of the series, are all distictly fresh-water types. As far as 

 observed, they are species of Viviparus, Goniohasis, and Unio, which can- 

 not be specifically distinguished from those found in the other Tertiary 

 beds of the basin. Throughout the shale series are numerous beds which 

 are more or less impregnated with bituminous material, and which are 

 characterized by the bluish-white color of their weathered surfaces. They 

 are often sufficiently rich in carbon to burn readily, and yield on distilla- 

 tion a considerable amount of mineral oil. They are most frequent in the 

 horizons which abound in fish remains, and it is from the decomposition of • 

 these that their carbonaceous material has probably been derived. The 

 lithological character of the beds indicates deposition in still, comparatively 

 deep waters. The material is a fine silt composed largely of carbonate of 

 lime, the other constituents being mainly finely-comminuted sand. The 

 following analysis of a specimen of the paper-shales was made by Mr. B. 

 E. Brewster : 



Insoluble residue 29.22 29.19 



Alumina 0.76 0.87 



Ferric oxide 2.16 2.20 



Lime 33.53 33.57 



Magnesia 0.56 0.68 



Carbonic acid 27.08 27.03 



Soda and potassa 0.38 0.38 



Water 6.27 6.20- 



99.96 100.12 



t 



