558 CALIFORNIA ACADEMY OF SCIENCES [Proc. 4th Ser. 



A single tooth was obtained by Mr. J. P. Buwalda from Mr. Williams, 

 who discovered it in extensive Orindan exposures about two and one- 

 half miles from the mouth of Tassajara Canyon, on the southwest side 

 of Mount Diablo. The specimen from Tassajara Canyon and the better 

 preserved tooth from Bolinger Canyon seem to represent different species. 

 The second specimen from near Bolinger Canyon is imperfectly preserved, 

 but is possibly different from the other two teeth. 



Nomlancf describes the occurrence of vertebrates in the 

 (Jacalitos) lower Etchegoin as follows: 



As has already been mentioned, a large quantity of fossil leaves and 

 petrified wood is found in the highly colored, perhaps land-laid beds 

 mapped as basal Jacalitos. This collection may, when carefully studied, 

 assist in determining the age of this formation. In these beds fossil re- 

 mains of the three-toed horse, Neohipparion mollc Merriam, were found. 



The finding of Pliohippus? in the gravels two hundred feet above the 

 basal Jacalitos, or in the bed mapped by Arnold and Anderson as their 

 lowest Jacalitos member, has already been mentioned in this paper. 



Above this no invertebrate or vertebrate fossils have thus far been 

 found until reaching the Glycymeris coalingensis zone, or lowest Etche- 

 goin. The Pliohippus stage of the development of the horse is repre- 

 sented here in the basal beds and a few hundred feet upwards. This 

 zone has therefore been called the Pliohippus coalingensis zone by Pro- 

 fessor Merriam. 



Merriam in the "Tertiary Vertebrate Faunas of the North 

 Coalinga Region," describes the relations of Neohipparion as 

 follows : 



The species represented by specimen 21370 is evidently distinct from 

 the Ricardo forms, and from all other described Hipparion species of 

 the Pacific Coast and Basin provinces. Whether it is a more or a less 

 advanced species than the Mohave form is not entirely clear. The 

 slightly greater length of crown, and the large, much-flattened protocone 

 may indicate a more advanced stage in the Coalinga species. The 

 Neohipparion species represented by no. 21370 is described as Neohip- 

 parion mollc. This species is characterized by length and narrowness 

 of upper molar crown, simplicity of enamel borders of the narrow fos- 

 settes, and unusually large anteroposterior diameter of the laterally 

 compressed protocone. . . 



The Jacalitos fauna as now known is characterized by the presence of 

 Neohipparion occurring only in the lowest beds, and by Pliohippus or 

 Protohippus apparently occurring a little higher than the Neohipparion 

 specimens in the basal portion of the section. 



Although Neohipparion gidleyi from the Sonoma group, 

 Neohipparion molle from the basal beds of the (Jacalitos) 

 Etchegoin formation north of Coalinga, and Hipparion platy- 

 style from Orinda beds two and a half miles southwest of 

 Tassajara Post Office, are specifically different, yet all three 



20 Nomland, J. O., Relation of the Invertebrate to the Vertebrate Faunal Zones of 

 the Jacalitos and Etchegoin Formations ,r\ the North Coalinga Region, California. Univ. 

 Calif. Publ., Bull. Dept. Geol., Vol. 9, No. 6, 1916. 



