396 A. HYATT — GEOLOGY OF THE TAYLORVILLE REGION. 



showed the existence of the Lias-- and Oolite in mount Jura, near Tay- 

 Lorville, Plumas county, California, and the need of making further 

 researches in this Locality. The second was gathered by Mr. J. S. Diller 

 and the author in the summer of 1890, and this, together with a third 

 collection made during the same season by Dr. Cooper Curtice, demon- 

 strated the existence of a distinct fauna in the Hinchman tuff. It is 

 only just to add that Dr. Curtice was the first to find this fauna at the 

 Locality named by Mr. Diller Curtict cliff. The fourth was collected in 

 the field season of 1891 by Mr. Diller and the author, assisted by Mr. 

 Iv C. Paul and .lames Storrs. This enabled us to define the different 

 faunas more exactly and brought to light, in a locality discovered by the 

 indefatigable exploration of Mr. Diller, an additional fauna in the Bick- 

 nell sandstone. The success and accuracy of the results attained in such 

 a difficult field and in so short a time are due to the exertions of Mr. 

 Diller, who surveyed the surface minutely, leaving literally not the 

 smallest outcrop unexamined: and his hearty cooperation and sym- 

 pathy with the work of the paleontologist cannot be repaid by this 

 formal public acknowledgment. The author desires also to take this 

 opportunity to return his thanks to Mr. I. C. Russell for similar favors 

 during the summer when they were associated at Taylorville and in the 

 more extended exploration of the known localities of the Jura and Trias 

 at the west. 



So far my experience with geologists has demonstrated that by coopera- 

 tion the paleontologist gathers larger and better collections in the same 

 time, being freed from the need of doing strictly geologic work, while the 

 geologist reaps a reciprocal advantage in being able to devote himsell 

 more exclusively to his own department. There is also a mutual ex- 

 change of criticism and information arising from the intimate relations 

 of the work done in both departments which has a decided influence 

 on the amount and quality of the results. The time saved is very 

 considerable, since it frequently happens that a new locality indicated 

 by a fvw fossils picked up by the geologist or one of his party can be at 

 once explored and the value of the evidence ascertained on the spot; 

 whereas had the fossils been taken home for examination, either they 

 would fail to justify any definite conclusions with regard to the age of 

 the rock or else he the occasion of another visit to the same place, in- 

 volving sometimes considerable expenditure in money and time. 



.Many of the species are not yet named, hut in all possible cases their 

 European congeners are cited ; and this is quite sufficient for the pur- 

 pose- of this preliminary notice, which was written in order that Mr. 



* Professor Jules Marcou had in his article "Geologie de la Californie" (Bull. Soc. Geol. de la 

 France, ser. ::. vol. si, !883, p. 1 1 1 1 stated thai the Hardgrave sandstone vvas Liassie. 



