\-oi.. IX) SMITH—CLIMATIC RELATIONS 165 



Weaver, Brachysphingns lirahis Gabb, Hetcrotcrma gabbi 

 Stanton, Neptunea miicronata Gabb. Ovula martini Dickerson, 

 Perissolax blakei Con., Turbinella crassitesta Gabb, Turritella 

 maccreadyi Waring, Turritella martinezensis Gabb, Turritella 

 pachecoensis Stanton, Turritella simiensis Waring, Urosyca 

 caudata Gabb, Urosyca robust a Weaver, Xenophora zitteli 

 Weaver, Hercoglossa merriami Dickerson, Nautilus stephen- 

 soni Dickerson, Nautilus hallidayi Waring. 



The Martinez horizon is not yet known north of CaHfomia, 

 but it is certain that tropical conditions extended at least that 

 far north at this time, and probably much further. No flora of 

 this age is known, but one is not needed to tell us the climatic 

 conditions. 



Summary. 



In the Eocene there is no suggestion of climatic zones, the 

 marine faunas being nearly the same from the equator to 

 Alaska. The fossil floras of California, Oregon, and Wash- 

 ington indicate tropical conditions on the land. 



In the Oligocene, tropical types, Aturia and Dolium, ranged 

 up to Puget Sound. Marine beds of this age are not yet 

 known in Alaska, but the Kenai flora belongs to the warm 

 temperate zone. 



In the lower Miocene the Californian faunas are tropical, 

 and Ficus, a tropical genus, occurs in the Clallam fauna of 

 Washington. It is not known whether the warm belt extended 

 up to Alaska, for lower Miocene faunas and floras are not yet 

 described from there. 



In the middle Miocene, (Empire), Phalium, a tropical genus, 

 is found in the region of Puget Sound, but there is a great 

 increase in the number of giant Chrysodomus, suggesting a 

 lowering temperature. 



The Santa Margarita-San Pablo, upper Miocene, with giant 

 Ostrea, numerous Trophon, Lyropecten and Astrodapsis, shows 

 that the climate was still subtropical in California. Faunas of 

 this age are not known in the Puget Sound region, while 

 those of the Alaskan Gulf indicate cooler water. On the 

 Asiatic side of the Pacific the warm belt extended to northern 

 Siberia, for Dall*^ has described from there a subtropical fauna. 



*' A subtropical Miocene fauna in arctic Siberia. Proc. U. S. Nat Mus., vol. 16, 

 (1893), pp. 471-478. 



