1920] Kew: Cretaceous and Cenozoic Echinoidea 33 



species are identical, though a few show close similarities. The Eocene 

 fauna bears approximately the same relationship, liaving in common 

 but four genera: Cidaris, Scutella, Bhynchopygus, and Schizastcr. 

 The eastern fauna is considerably larger, having nineteen more genera 

 than the western. The Oligocene retains about the same relationship 

 as the Eocene, but the comparatively meager fauna of the Pacific 

 Coast does not permit a satisfactory comparison. In marked con- 

 trast to the former periods, the Miocene and Pliocene of the west coast 

 possess the most abundant fauna of the temperate type. Only two 

 genera, Scutella and Schizaster, are common to the fauna of the Gulf 

 and Atlantic provinces. The western fauna at this time shows a great 

 development of the genus Scutella., whereas the only eastern species 

 is Scutella ahoii Conrad, which is of an entirely different type from 

 the western forms. Furthermore, the many species of Dendraster and 

 Astrodapsis, forms not occurring on the Atlantic Coast, are especially 

 abundant on the Pacific. On tlie other hand, genera such as Laganitni 

 and Pcriarelius, relatively abundant in the Gulf fauna at this time, 

 are not present among the west coast fauna. During the Pleistocene 

 some intermingling of the faunas took place since Sfrenigylejccntreifus 

 drobadiicnsis Miiller and Scutella parma (Lamarck) are present on 

 both of the northern coasts of North America. 



The Indian Cretaceous fauna does not seem to have so intimate a 

 relationship to the Pacific Coast fauna as does the interior and the 

 Gulf provinces of North America. Although the same genera are 

 common, the specific forms are not so closely allied. In the Eocene 

 all of the genera of the west coast are present in the Indian fauna 

 of this period, but none of the species are the same. Beginning 

 with the Oligocene, the genera become more distinct, though such 

 forms as Bhynchopygus and Schizaster continue to be common to both 

 regions. On tlie California coast the Scutellidae is the dominant 

 family, whereas the Indian fauna acquires a tropical aspect, having 

 forms such as Clypeaster and Breynia. 



The Carrizo Creek fauna, of the Gulf of California province, being 

 of the tropical type can be compared to tlie Gulf of Mexico and Panama 

 assemblages. Although the genera Cidaris and Encope are common 

 to this and to the Pliocene fauna of the Gulf of Mexico province, it 

 shows its closest resemblance to the Recent fauna of the Gulf of 

 California, the species differing only very slightly. 



In summarizing, it may be stated that the Cretaceous and Eocene 

 faunas of the Pacific Coast province are not only closely related to 



