1920] 



Kew: Cretaceous and Cenozoic Echinoidea 



47 



Pliocene of the Santa Ynez River region, a variety with a slightly less 

 eccentric apical system but retaining the wide anterior petal is met 

 with. This variety is of larger size and the less eccentric apical system 

 indicates that it is a forerunner of the Upper Pliocene dendrasters, in 

 which the apical system becomes still less eccentric. 



D. excentrlcus (Eschschoitz) 



O. diegoensis venturaensis Kew 



D. diegoensis diegoensis Kew 



C. oregonensis, var. gibbosus 

 Kew 



D. ashleyi (Arnold) 

 D. gibbsii, var. humilis Kew 



D. Iiesperis, var. gibbosus Kew 



I 



D. hesperis Kew 



D. perrini (Weaver) 

 i 



D. amoldi Twiichell 



I 



D. coalingaensis Twitchell 



D. gibbsii (Re'mond) 



Dendraster jacalitosensis Kew 



Calaster oregonensis Clark 



SCUTELLA 



Kg. 5. Phylogenetic tree for the Genus Dendraster and Subgenus Calaster. 



During the Upper Pliocene two distinct forms were present in the 

 deposits of southern California, while farther to the north, echinoderms 

 indistinguishable from D. excentricus (Eschschoitz) of the Recent 

 epoch lived. In the San Diego formation the D. diegoensis diegoensis 

 Kew shows some differences from the former, which are probably due 

 to environment or perhaps a slightly higlier degree of specialization. 



