1920] Kew: Cretaceous and Cenozoic Echinoidea 



31 



cerning the sea urchins of this period it may be concluded that they 

 were not numerous, though they had a uniform distribution. 



During the Eocene more or less the same condition prevailed, and, 

 as in the latter period, the echinoderms were of wide distribution over 

 California, the species Schizasfer lecontei Merriam, 8. diaMoensis Kew, 

 and Spatangus pachecocnsis Pack occurring from Santa Barbara 

 County to the San Francisco Bay region. Shallow water forms, such 

 as Scutella, were absent from the soiathern part of the state, but were 

 present sparingly in the vicinity of San Francisco and Oregon. 



The Oligocene and more especially the Neocene, in marked contrast 

 to the Cretaceous and Eocene, became favorable for harboring many 

 shallow water forms. In the Oligocene Scutaster andersoni Pack, a 

 littoral scutellid form, has a relatively wide distribution, being found 

 in the southern end of the San Joaquin Valley and also in Contra 

 Costa County. Although the number of species is large, the Lower 

 Miocene fauna is peculiar in that the majority are confined to certain 

 localities in the southern part of the state. Those having the widest 

 geographic range are Scutella merriami (Anderson) and S. norrisi 

 Pack, which are found in Orange County and in the Diablo Range 

 as far north as the vicinity of Coalinga. The Upper Miocene fauna 

 shows that special geographic subprovinces were present which con- 

 tinued through the Pliocene. Each subprovince contained a fauna 

 which, in the aggregate, had forms that were specifically different from 

 those of other subprovinces, yet a few species were common to all. 



During the Miocene the California province as a whole may be 

 divided into the following subprovinces: (1) Northern, including San 

 Francisco Bay, Mount Diablo region, north to Puget Sound; (2) San 

 Joaquin Valley ; and ( 3 ) Outer Coast Ranges, which includes the 

 Salinas Valley, Santa Maria, and Los Angeles districts. In all these 

 Astrodapsis tumidus Remond and A. ivhitneyi Remond were common 

 during Upper San Pablo (Santa Margarita) time. A. major Kew, 

 occurring in the uppermost part of the San Pablo at Mount Diablo, 

 is a species very closely allied to the A. arnoldi group, which is the 

 most prevalent type in the lower part of the Etchegoin (Jacalitos) 

 formation of the two southern subprovinces. Dendraster arnoldi 

 Twitchell is another form common to the latter two formations in 

 Fresno and Santa Cruz counties. In the Upper Etchegoin the fauna 

 as a whole changes and the subprovinces seem even more distinct 

 faunally than before. The San Francisco Bay area, which at this 



