196 CALIFORNIA ACADEMY OF SCIENCES [Proc. 4th Ser. 



basin and the abundance of this Volute, a characteristic tropi- 

 cal form, in the Los Angeles basin at the Simi hills localities 

 is significant. The great variety of Turritcllas and their abun- 

 dance is another feature of the Martinez fauna of the Simi 

 hills. Tiirritella martinez, Tiirritdla macreadyi, Turritella 

 pachecoensis, Turritella, new species, a, Turritella, new species, 

 b, and Turritella, new species, c, are Turrit ellas whose orna- 

 mentation suggests life in tropical or semi-tropical waters. 

 Pseudoliva hozvardi described from the Martinez of the Rock 

 Creek region also occurs in the Simi hills. Apparently this 

 highly specialized form is limited to the Los Angeles basin. 

 The genus Cerithium is now represented by two species in the 

 Los Angeles basin, Cerithium butterzvorthi and Cerithium, 

 new species. Ovula, new species, was collected in the Simi 

 hills in two or three localities. The much greater variety and 

 higher ornamentation of the Pleurotomidce in the fauna of the 

 Simi hills is in decided contrast with the simpler types of this 

 family in the San Francisco basin. This evidence indicates 

 then that the Martinez of the Los Angeles basin was deposited 

 in sub-tropical seas, w^hile that of the San Francisco basin was 

 deposited in waters which more nearly correspond to temperate 

 conditions of today. 



Such studies of climatic conditions enable the student of the 

 distribution of life to complete, in part, a picture of the past. 

 That climatic changes in the past were some of the principal 

 causes of faunal changes is more and more being realized as 

 the invertebrate faunas of the Pacific Coast and their relation- 

 ships are becoming known. The closing or the opening of 

 certain portals or gateways such as occur in the Panama and 

 Bering regions have not only influenced the distribution of land 

 animals but marine invertebrates as well. That the Bering 

 portal was closed during Martinez time is strongly suggested 

 by the occurence of a Martinez invertebrate fauna in Japan. 

 Incidental to the closing of this gateway, a shifting of oceanic 

 currents resulted, and this in turn was reflected by the fauna 

 of the lower Eocene. In conclusion: well marked climatic 

 zones were present during lower Eocene time in contrast with 

 the genial climate of the Tejon whose faunas of the far north 

 still bear evidences of a tropical origin. 



