USE OF DILLER'S COLLECTIONS. 249 



White's Classification of the California Cretaceous. — DrC. A. White, whoso 

 work on the Cretaeeous of California has already been referred to, also 

 recognized two divisions in the Shasta, to which he gave the local names, 

 Knoxville and Horsetown beds, although he believed them to be closely 

 related ; and several species of the Horsetown fauna were afterward 

 found associated in the same strata with Aucella, the characteristic fossil 

 of the Knoxville beds, near Riddles, Oregon.* It may therefore be 

 regarded as established that the Knoxville beds should not be considered 

 distinct from the remainder of the Shasta formation, although they may 

 usually be recognized by the great abundance of Aucella, a fossil that 

 seems not to range into the upper part of the scries. 



The great apparent difference in the faunas of the Shasta and the < hico 

 formations at the localities studied by him led Dr White to believe that 

 there is a break between these two formations, representing a great time- 

 hiatus.f although they are apparently conformable. The list of species 

 assigned to each formation by Mr Gabb also seemed to justify this belief, 

 but the sequel will show that the stratigraphic position and the vertical 

 range of many of the species were very imperfectly known until quite 

 recently. 



Relation of Shasta and Chico Faunas. 



Identity of Fauna* indicated. — Various members of the United States 

 Geological Survey working in California and Oregon during the last few 

 years have from time to time made small collections of Cretaceous fossils 

 that have been submitted to Dr White for examination. The largest of 

 these collections was received from Mr J. S. Diller in 1889, and was 

 assigned to me for study and identification, under the direction and 

 supervision of Dr White. The collection embraced small lots of fossils 

 from about seventy-five different localities in northern California and 

 southern Oregon, the most of which are in the valley of Sacramento river.;}; 

 There were usually only a few species of fossils from each locality, as they 

 were collected by the geologists in connection with other field-work and 

 without any attempt at making exhaustive collections. The fossils were 

 identified and those from each locality were, so far as practicable, assigned 

 to tbe Shasta or to the Chico-Tejon, in accordance with the distribution 

 of species in those formations given by Mr Gabb. But some of the locali- 

 ties seemed to show a mixture of Shasta and Chico species, and when 



*See G. F. Becker, Notes on the early Cretaceous of California and Oregon : Bull. Geol. Soc. Am., 

 vol. 2, 1891, pp. 204-205. 



fSee Hull. U. S. Geol. Survey, numbers 15, 22, 51 and 82. 



J For description of the geology of this region and further discussion of the paleontology see Mr 

 Piller's paper, this volume, pp. 205-224. 



