1920] Kew: Cretaceous and Cenozoic Echinoidea 



43 



possess well developed astrodapsid features, having distinctly elevated 

 petals, grooved interambulacral areas, and simple but marked ambu- 

 lacral furrows. 



The development of the main group, that of Astrodapsis tumidus, 



A. femandoensis Pack 



A. major Kew 



A. jacalitosensis Arnold 



A. coalingaensis^var. grandis Kew 



A. califomicus Kew 



A. scutelliformis Kew 



A. amoldi spaliosus Kew A. arnoldi, var. fresnoensis 



Kew 



A. amoldi peltoides 



Anderson and Martin 



A. amoldi crassus Kew 



A. cuyamanus Kew 



I 



A. whitneyi Remond A. coalingaensis Kew 



A. tumidus (small thick form) 



A. alius Ke 



A. amoldi amoldi (Pack) 



A. margaritanus Kew A. omatus Kew 



A. eierboensis (Kew) 



A. brewerianus, var. diabloensis Kew 

 I 



Aslrodapsis brewerianus (Remond) 

 SCUTELLA 



Fig. 4. Phylogenetic tree for the Genus Astrodapsis. 



gives rise later on to a variety which has been designated as A. tumidus 

 (small thick form). This variety also occurs in the Upper San Pablo 

 (Santa Margarita) formation of the Salinas Valley district, which 

 shows it to be fairly widespread. Immediately after this form of 

 A. tumidus became extinct, three new groups made tlieir appearance : 



