600 THE JOURNAL OF GEOLOGY. 



limestone ridges are cut through by the McCloud river about 

 nine miles above the U. S. Fisheries, but continue along the 

 west bank of the river about ten miles further to the north. 

 After that they reappear at intervals in the same strike as far as 

 the county line, getting nearer to the Sacramento river. The 

 geological map of Shasta county, published by H. W. Fairbanks, 1 

 shows the distribution and relations of the McCloud limestone. 

 J. D. Whitney 2 estimates the thickness of the McCloud lime- 

 stone at about 1,000 feet, and says that it lies conformably 

 between metamorphic slates. H. W. Fairbanks 3 says that the 

 thickness is nearer 2,000 feet, which agrees with the observa- 

 tions of the writer. 



Fauna of the McCloud Limestone. From the locality at Bass' 

 ranch F. B. Meek, in Volume I. of the Paleontology of Cal- 

 ifornia, cites the following species : 



Fusulina cylindrica, Fischer. 



" " var. gracilis, Meek. 



" {Schwagerina) robusta, Meek. 

 Lithostrotioti californiense, Meek. 



" sublaeve, Meek, 



sp. 

 Clisiophylluni gabbi, Meek. 

 Orthis conf. carbonaria, Swallow. 

 Productus semireticulatus, Martin. 

 Rhynchonella sp. 



Spiriferina conf. cristata, Schlotheim. 

 Spirifer lineatus, Martin. 

 Retzia compressa, Meek. 

 Euotnphalus whitneyi, Meek. 



Several days of collecting in the region of Baird failed to 

 increase this list. Taken by itself the fauna would not be 

 characteristic of Upper Carboniferous, and indeed it is arbitrary 

 to draw the line at the base of the limestone. Even Fusulina 

 cyli?idrica, which in the region east of the Rocky Mountains 



'California State Mining Bureau, Eleventh Annual Report, 1893. 

 2 Geol. California, Vol. I., p. 326. 



3 California State Mining Bureau, Eleventh Annual Report, 1893. Geology and 

 Mineralogy of Shasta County, p. 36. 



