300 University of California Publications in Geology [Vol. 8 



California climate during Martinez time was like the present. Pos- 

 sibly the climate in Martinez time was more uniform along the Cali- 

 fornia coast that it is today. 



The faunas from Rock Creek and the Santa Ana Mountains are 

 markedly different from those of the Tejon, upper Eocene, and Chico- 

 Cretaceous. This difference is as great as was found in a study of 

 the relationship of the faunas of these groups in the San Francisco 

 Basin of the Martinez. 



DESCRIPTION OF NEW SPECIES 

 CRASSATELLITES BRAINERDI, n. sp. 

 Plate 29, figure 2 



Shell trigonal, high, with a rounded anterior extremity and sharply 

 pointed posterior extremity. The beak is situated about one-third of 

 the distance from the anterior end. The slightly convex posterior 

 dorsal margin slopes steeply to an angulated posterior end. The 

 gently rounded anterior dorsal margin is moderately excavated under 

 the beaks. The shell has a medium sized, heart-shaped lunule and 

 a long, narrow, indistinct escutcheon. Base, broadly rounded. 



This species resembles Crassatellitcs unioides (Stanton) closely, 

 but it has a more steeply sloping posterior dorsal margin and a well- 

 rounded, anterior extremity. 



Named in honor of Edward Brainerd who contributed original 

 material of this species. 



Dimensions. — Height, 40 mm. ; length, 45 mm. 



Occurrence. — University of California Locality 2233, Martinez 

 Group in the Santa Ana Mountains. 



SAXIDOMUSC?) NOBLEI, n. sp. 

 Plate 29, figure 1 



Shell oval in outline, thick, with rather low beaks which are 

 situated two-fifths of the length from anterior extremity. The pos- 

 terior dorsal margin, which is but slightly convex, slopes gently to a 

 well-rounded posterior extremity. The shell on the type specimen is 

 decollated and the shape of this margin was observed in other speci- 

 mens. The anterior dorsal margin is only half as long as the posterior 

 dorsal margin, and is gently concave owing to a slight excavation 

 under the beaks. Anterior extremity, broadly rounded. Base, evenly 

 rounded. 



