40 University of California Publications in Geology [Vol. 8 



made in June, 1912, in company with Mr. Walter A. English and Mr. 

 M. Kew, and the second with Mr. John P. Buwalda, during April and 

 May, 1913. In the collections obtained on these expeditions are 

 several echinoids which have not been described. A description of 

 these new forms, together with a brief account of their occurrence 

 and the relationships of the fauna, is presented in the following paper. 

 The writer acknowledges his indebtedness to Dr. John C. Merriam, at 

 whose suggestion the work was undertaken and under whose super- 

 vision it was carried on, for much valuable aid in connection with this 

 study. 



The region visited was briefly described by W. P. Blake in 1853, 

 and a few fossils from this locality were described by T. A. Conrad. 1 

 H. W. Fairbanks 2 examined this area in 1893 and gave a short descrip- 

 tion of the geology. Later reports were published by Bowers 3 and 

 Mendenhall. 4 Arnold 5 published a partial list of the fauna, giving 

 the age of the beds as Lower Miocene and later more definitely cor- 

 related them with the Etchegoin formation of Middle California. 



Occurrence 



The collecting done by the writer was limited to the Tertiary beds 

 of the Carrizo Creek formation in the sections at Carrizo Creek, around 

 Coyote Mountain (also known as Carrizo Mountain), and in the 

 vicinity of Yuha Buttes. At all localities fossils occur abundantly 

 and are generally well preserved. 



Carrizo Creek is in the western part of the Imperial Valley 

 about fifteen miles north of the Mexican Boundary. The creek has 

 its source south of the boundary in the mountains which border the 

 coast of Southern California and Lower California, and flows north, 

 turning east as it approaches the desert. At this point its course 

 lies in a broad valley immediately north of Coyote Mountain. It is 

 in this valley that the type section of the Carrizo formation is 

 situated. 



1 Conrad, T. A., Pacific Eailroad Eeports, vol. 5, pp. 104 and 174-176, 1856. 



2 Fairbanks, H. W., Eleventh Annual Eeport of the State Mineralogist of 

 California, pp. 88-90, 1893. 



s Bowers, Stephen W., Eeconnaisance of the Colorado Desert Mining District, 

 California State Mining Bureau Eeports, 1901. 



i Mendenhall, W. C, Journal of Geology, vol. 18, no. 4, pp. 336-355, 1910. 



s Arnold, Ealph, Science, n.s., vol. 19, p. 503, 1904; U. S. Geol. Surv. Profes- 

 sional Paper no. 47, p. 21, 1906; Bull. U. S. Geol. Surv. no. 396, p. 44, 1909; Willis 

 and Salisbury, Outlines of Geologic History, pp. 244-245, 1910. 



