THE AMYZON BEDS. 743 



determination of the genus is not final. It however remains, that this fish 

 fauna is different from that of the Green River beds, and the modern aspect 

 of the genera points to an age even later than the Bridger. It is evident 

 that the pertinence of this series of rocks to the Green River formation, 

 asserted by King, cannot be maintained. 



I publislied the first notice of this formation, which I examined at an 

 exposure in the northeastern portion of Nevada, twenty-five miles northeast 

 of Elko, on the Central Pacific Railroad. The outcrop is on the south side 

 of the low mountain range bounding Humboldt Valley on the north. The 

 beds are exposed in a drift and adjacent cutting, and a shaft 200 feet in 

 depth. The strata are argillaceous and in some degree calcareous, and are 

 very thinly laminated ; so much so as to resemble thin brown, or black 

 paper in some portions of the series. They are highly carbonaceous, and 

 burn freely ; some of them with the odor of amber, which appears as a 

 gloss on some of the laminae Descending 60 or more feet through these 

 shales, we reach a bed of solid argillaceous material of a dark-green color. 

 This can be removed with the pick, but hardens on exposure to the atmos- 

 phere. It contains fresh- water shells. The first bed of coal is two and a 

 half feet in thickness, with one or two laminae of slate. The second bed is 

 12 feet deeper, and is about 3 feet in thickness. In quality both resemble 

 cannel, but have more luster. 



Masses of the laminated shales resemble the braun kohle of Bonn, 

 Prussia ; and they contain fossils disposed in the same way. These con- 

 sist of multitudes of leaves, mostly of dicotyledonous plants ; of mollusks, 

 insects, and fishes ; the last two often in a fine state of preservation. The 

 mollusks present forms similar to Planorbis, Viviparus, etc. The insects 

 are mostly diptera, and some of them are nematocera. The fishes are fresh- 

 water forms, of which, perhaps, four species were procured. I made an 

 examination of two of these, and found them to represent both species and 

 genera new to science One of these is of interest, as furnishing the first 

 evidence of the appearance of the Catostomoid type, now so extended in 

 North America ; the other is allied to a genus which has been discovered 

 in the Eocene shales of Green River. 



The shales are considerably less indurated in general than those of 



