94 



University of California. 



[Vol. 2. 



clays, limestones, and eruptives, which is well developed in the 

 hills east of Berkeley, California, and belongs, according to Prof. 

 A. C. Lavvson, to the lower division of the Pliocene.* They are 

 found at various horizons in clays and limestones, from the lower 

 to near the upper portion of the series. 



" Most of the localities at which the Ostracoda were abundant 

 (Nos. 585, 589, 26, 297), seem to be near the middle portion of the 

 series. Here they are enormously abundant, often forming layers of 

 impure limestone a foot or more in thickness. The limestone strata, 

 of which there are usually several, alternate with beds of either 

 clayey or tufaceous material ten or more feet thick. The condi- 

 tions favoring growth and multiplication of the Ostracoda seem to 

 have been particularly favorable in this region during the period in 

 which these limestone beds were laid down. Lower down in the 

 series, at locality No. 587, Ostracoda are quite abundant in a soft 

 blue shale. Near the top of the section they are frequently pres- 

 ent, but not in such numbers as to form a marked feature of the 

 rocks." 



LOCALITIES. 



The five rock samples received are localized as follows : " No. 

 585.1 Wild Cat Canon, opposite the Caves." From this locality 

 two specimens were received. One is an extremely hard and com- 

 pact limestone, of a pale brown color, and crowded with the carapaces 

 of Ostracoda. This rock appears to have undergone a certain amount 

 of compression, for the surfaces of the Ostracod- valves are im- 

 pressed and indented by one another ; and it is due to this fact that 

 not very many valves were obtained from this specimen, which could 

 be definitely described. The other specimen is from a friable cal- 

 careous rock of an ocherous brown color. This rock is almost 

 entirely made up of the valves of Ostracoda. 



"No. 587. Railroad cut, one-eighth of a mile north of Bryant 

 station, C. & N. R. R., San Pablo Valley." This somewhat shaley 



*" The geology of the region in which this series occurs has been subjected 

 to detailed study by Professor Lawson, who is preparing a monograph on the 



subject." — j. c. m. 



|The numbers here used refer to numbered fossil localities, a record of 

 which is kept at the State_University. 



