MESOZOIC TIME — TRIASSIC AND JUKASSIC. 



759 



" g'uard." 



(A perfect bone of similar nature is shown in 



posterior portion or 

 Eig. 1300, page 782.) 



The Jurassic of Taylorville, Plumas County, CaL, has afforded Hyatt 

 many species, and among them, from the Upper Lias, Pinna expansa, Fig. 

 1201 ; from the Oolyte, Lima Taylorensis, 1199, and Entolium gibbosum, 1200 ; 

 and from the Coral bed, Stylina tubuUfera, 1202. The Ammonite, Arnioceras 

 Nevadimm (Fig. 1198) is from the Jurassic at Volcano, Nev. {Am. Jour. 

 Conch., vol. v., pi. 3). 



1198-1202. 



Kg-. 1193, Arnioceras Nevaduum ; 1199, Lima Taylorensis; 1200, Entolium gibbosum; 1201, Pinna expansa; 



1202, Stylina tubulifera. Original. 



Shells of the species of Aucella from the Auriferous slates are repre- 

 sented in Figs. 1203-1205. Aucella Erringtoni (so named in commemoration 

 of the first discoverer of fossils on the Mariposa estate, Miss Errington) 

 occurs in the partially metamorphic upturned slates ; Fig. 1203 represents 

 the common form ; and 1204, a narrower variety occurring in the sandstone. 

 The Triassic genus Monotis is continued, one species of which is shown in 



1203 



1203-1205. 

 1204 



1205 



MOLLUSK. — Aucella Erringtoni. Meek. 



Fig. 1193. Trigonia, related to Myophoria, has its first American species. 

 Other characteristic genera of Lamellibranchs are Tancredia, Lima, Gervillia, 

 Chryphcaa, Inoceramus, and Pholadomya. 



