MESOZOIC TIME TKIASSIC AND JURASSIC. 



757 



Cockroach group (Blattariae) ; and out of the 17 species, 11 have the wings 

 like those of the Paleozoic species as to transparency and nervures, and 

 belong partly to described genera, while six are Mesozoic in the character of 



1190 



1190-1191. 

 1190 «. 



1191a. 



1191 



Ammonite Family. 



■Fig. 1190, Sageceras Haidlngerl ; 1190 a, same in profile; 1191, Trachyceras Whitneyi ; 

 1191 a, same, showing form of pockets. Gabb. 



the nervures, and in having the fore wings more or less opaque, approach- 

 ing thus the modern kinds. This commingling of Paleozoic and Mesozoic 

 types leads Scudder to the conclusion that the beds are Triassic, although 

 referred by Lesquereux, on the ground of some imperfectly preserved fossil 

 leaves, to the Permian. 



The Trias of Idaho, which Hyatt considers the lowest yet found in this country, 

 contains, according to White (1879), Terehratula augusta, T. semisimplex, Aviculopecten 

 Idahoensis Meek, A. Pealsi, A. altus, Eumicrotis curta Mk. & H., Arcestes cirratiis (?), 

 Meekoceras aplanatum, and others. 



In western Nevada, West Humboldt region (King), Orthoceras Blakei, Sageceras 

 Haidingeri, Trachyceras Whitneyi^ Arcestes Nevadensis Mk., A. Gabbi, Myophoria alta, 

 Monotis subcircularis, Halobia dubia, Avicula Homfrayi, Hnlohia (Daonella) Lommeli, 

 Pecten deformis, Pentacrinus asteriscus (?), etc. Hyatt reports from Desatoya Moun- 

 tains, New Pass, and Walker's Lake of Nevada, besides some of the above forms, Gym- 

 notoceras rotelUforme, Trachyceras Whitneyi. 



In the Taylorville region, Plumas County, Cal., occur, as identified by Hyatt (1829) 

 from the successive beds : (a, or lowest) slates, the Monotis bed, Monotis subcircularis 

 Gabb (which he says may be M. salinaria Schloth.), Pecten deformis Gabb, and at the 

 top, Daonella tenuistriata Hyatt ; (b) a limestone, the Khabdoceras bed, with, besides the 

 preceding, species of ISfucula, Lima, Modiola, Myacites, Rhynchonella, and Ammonites of 

 the genera Ammonites and Arcestes, Bhabdoceras Busselli (a strait Ceratite), with Belem- 

 nites of the genus Atractites ; (c) the Halobia bed, with species of Halobia, Arcestes, 

 Tropites ; (d) the Hosselkus limestone, with the same Ammonites, and others of the genera 

 Ceratites, Badiotites, and Juvavites. The upper subdivision is referred by Hyatt to the 

 Lower Carnic of the Alpine (Upper) Trias, and the others to the Upper Noric. 



From British Columbia have been reported by Whiteaves, who has described several 

 of the species as new from Queen Charlotte Islands, the Ammonites Arcestes Gabbi, 



