'.] 



61 



represented in the Bridger by Pappicthys, but in the former genera the 

 characteristic parts have not yet been seen in the South Park specimens, so 

 tliat here also the determination of the genus is not final. It, however, re- 

 mains that this fish fauna is different from that of the Green River beds, 

 and tlie modem aspect of tlie genera points to an age even later than the 

 Bridger. It is evident that the pertineace of this series of rocks to the Green 

 River formation, asserted by King, cannot be maintained. 



In the American Naturalist for May, 1879, I named the strata of this 

 epoch that of the Arayzon beds, from the characteristic genus which it 

 includes, and refer it to the later Eocene or early Miocene eras. Its fish 

 fauna includes ten species, distributed, as follows : Trichoplianes Cope, 3 

 sp. ; Amyzon Cope, 4 sp. ; Bhineastes Cope, 1 sp. ; Amia L., 2 sp. 



There is a series of calcareous and silico-calcareous beds in Central Utah 

 in Sevier and San Pete counties, which contain tiie remains of different 

 species of vertebrates from those which have been derived from either the 

 Green River or Amyzon beds. These are Emys, sp. ; Crocodilus, sp. ; 

 Clastes cuneatus Cope, and a fish provisionally referred to PHscacara under 

 the name of P. testudinaria Cope. Dr. Hayden first directed my atten- 

 ti(m to these fossils, and I am indebted to the kindness of the director of 

 the Museum of Salt Lake for the loan of specimens. I afterwards sent a 

 collector to the region, and he obtained a number of fossils. 



There is nothing to determine to which of the Eocenes this formation 

 should be referred, but it is tolerably certain that it is to be distinguished 

 from the Amyzon beds. In its petrographic characters it is most like the 

 Green river, as it consists in large part of shales. The laminae are gener- 

 ally thicker than those of Green and Bear Rivers. The genera Crocodilus 

 and Clastes have not been found heretofore in Green River beds, although 

 they are abundant in the formations deposited before and after that period. 

 Until its proper position can be ascertained, I proposed that the formation 

 be called the Manti beds. (See American Naturalist, April, 1880.) 



The regions of the John Daj^ River and Blue Mountains, furnish sections 

 of the formations of Central Oregon. Above the Loup Fork or Upper 

 Miocene, there is a lava out-flow, which has furnished the materials of a 

 later lacustiine formation, which contains many vegetable remains. The 

 material is coarse, and sometimes gravelly, and it is found on the Columbia 

 River, and I think also in the interior basin. Prof. Condon, in his unpub- 

 lished notes call this the Dalles Group. It is in turn overlaid by the beds 

 of the second great volcanic outflow. Below the Loup Fork follows the 

 Truckee Group, so rich in e.xtinct mammalia, and below this a formation of 

 shales. These are composed of fine material, and var}^ in color, from a 

 white to a jiale brown and reddish-brown. They contain vegetable remains 

 in excellent preservation, and undeterminable fishes. The Taxodium 

 nearlj' i-esembles that from the shales at Osiuo, Nevada, and on various 

 grounds I suspect that these beds form a part of the "Amyzon Group" 

 (American Naturalist, June, 1880), with the shales of Osino and of the 

 South Park of Colorado. Below these, is a system of fine grained, some- 



