MESOZOIC TIME — TRIASSIC AND JURASSIC. 



749 



The Lias and earlier Oolyte appear to be unrepresented along the Coast region and 

 Plateau belt of British America (G. M. Dawson). 



Jurassic beds, related in fossils to those of Taylorville, occur also in the Pit River 

 region on the western and northern borders of the Sacramento valley, with Triassic and 

 Carboniferous below, and are covered unconf ormably by the Cretaceous ; also on the 

 upper waters of Crooked River, in the Blue Mountains of Oregon ; and, according to Hyatt, 

 these areas were connected, during the Lias, with that of western Nevada. 



Small Jurassic areas are laid down on Castillo's geological map of Mexico, in the states 

 of Sonora, Coahuila, San Luis Potosi, Queretaro, Hidalgo, Puebla, and others near the east- 

 ern border of the great central plateau, and also in Colima near the coast. The beds, 

 according to Agiiilera and Ordonez (1893), contain Aucellas, and Ammonites of the genus 

 Pensphinctes, and pass conformably into the overlying Cretaceous. 



In the Arctic Regions, the Jurassic (Lias '?) has been identified far north on Prince 

 Patrick Island and near the northwest extremity of Bathurst Island, and on Exmouth 

 Island and other places in the vicinity. At the locality on Bathurst Island, a vertebra of 

 a Saurian, Arctosaurus Osborni, has been found ; and on Exmouth Island, remains of an 

 Ichthyosaurus. 



The Jura-Trias regions of part of Utah and Nevada are mapped (in colors) in King's 

 40th Parallel Report (1878); and of Idaho and part of Utah, by Peale, Endlich, and St. 

 John, in the Hayden Expedition Report for 1878 ; and of part of California by Diller 

 (1893) in the Atlas of the U. S. Geological Survey, on the sheets of the Lassen Peak 

 district. 



1156-1160. 



1157 



Fig. Il.i6, Podozamites Emmonsi ; 1157, Pterophyllum Pdegeri ; 115S, Clathropteris rectiuscula; 1159, Oligo- 

 carpia (Pecopteris) robustior, part of a frond in fructification ; 1160, Tasniopteris linnsifolia. Figs. 1156- 

 1159, E. Emmons ; 1160, E. Hitclicock, Jr. 



