Mekriam.] 



Triassic Tchth yopterygia . 



65 



FORMS FROM UPPER TRIASSIC OF NORTHERN 

 CALIFORNIA, SHASTASAURUS GROUP. 



OCCURRENCE. 



All of the saurian material which has so far been discovered 

 in the Shasta region has been found in two limestone areas lying 

 in the northern part of the county. Most of the specimens have 

 been obtained from a large area between Squaw Creek and Pitt 

 River, a few miles north of Winthrop Post Office. It was in this 

 region that Professor Smith made the first discovery of saurian 

 remains in, 1893. A few fragmentary but interesting specimens 

 have also been found in a small outcrop on the western slope of 

 Bear Mountain, twenty miles northeast of Redding. Mr. O. B. 

 Sherman of Bear Valley was the first to notice saurian bones at 

 this locality. > 



The beds in which these remains occur have been described by 

 Dr. H. W. Fairbanks* and Professor James Perrin Smith. t 

 They are considered by Professor Smith as the equivalent in age 

 of the Hosselkus limestone. The following extract from his 

 paper cited above gives unquestionable evidence as to their age: 



" The Hosselkus limestone may be conveniently divided into 

 three divisions, the lowest of which is the Trachyceras beds, so 

 called from the large number of that genus found at this horizon. 



"These beds are about fifty feet thick, auqV are composed of 

 rather hard, pure limestone, made up almost entirely of fossils; 

 a large majority of all the Triassic species were taken from this 

 horizon. 



" The best collecting ground was found on the ridge between 

 Squaw creek and Pitt river, about three miles northeast of 

 Madison's ranch. The following fossils were collected at this 

 locality : 



Arpadites aff. A. cinensis, Mojsisovics. 

 Balaton ites sp. group of B., Arietiformes. 

 Balaton ites sp. group of B., Gemmati. 

 Polycyclus conf . henseli, Oppel. 

 Tirolites conf. foilaceus, Dittmar. 



*Am. Geol. July, 1894, Vol. XIV, p. 27. 

 t.Jour Geol. Oct., 18<)4, Vol. II, p. 606. 



