126 CALIFORNIA ACADEMY OF SCIENCES [P«oc. 4th Sm. 



We have thus a series of columnar sections from Eocene 

 to the present, strung^ out from the equator to the Gulf of 

 Alaska, at intervals of from 5° to 15°, giving good repre- 

 sentatives of the Tertiary and Quaternary faunas of the tropi- 

 cal, subtropical, warm temperate, cold temperate, and sub- 

 boreal zones; also for comparison, the Recent faunas of the 

 same latitudes. We have also fossil floras of Eocene, Oligo- 

 cene, Miocene and Pliocene, to check the results obtained from 

 the faunas. 



Quaternary faunas, as should be expected, are better repre- 

 sented than Tertiary, though this is true only on the West 

 Coast. We have Quaternary faunas from Manta, Ecuador, 

 and the Galapagos Islands under the equator ; Magdalena Bay, 

 Lower California, lat. 24° 30' N. ; San Ignacio Lagoon, lat. 

 27° N. ; Cerros Island, lat. 28° N. ; San Diego to Santa Bar- 

 bara, southern California, lat. 33° to 34° 30' N. ; San Fran- 

 cisco Peninsula, lat. 37° 30' N. : Cape Blanco, Oregon, lat. 

 43° N. ; Victoria, Vancouver Island, lat. 48° N. ; Douglas 

 Island, Alaska, lat. 58° N.; and Cape Nome, lat. 64° N. 

 These Quaternary faunas range from tropical to boreal, as they 

 should, keeping pace with the Recent faunas, but showing in 

 many cases great displacement of the isotherms, as compared 

 with the present. 



The Pliocene faunas, stretched out in the same way, show 

 still greater displacement of the isotherms in some cases, 

 which becomes more strongly marked in the Miocene. The 

 extreme is reached in the Eocene, when a tropical temperature 

 extended from the equator to Alaska, strongly contrasted with 

 lower Quaternary, when a sub-boreal temperature extended 

 down nearly to San Diego. 



The constant fall of temperature from Eocene to lower 

 Quaternary, and the temporary rise in the upper San Pedro, 

 were not confined to the West Coast, being apparent also in 

 the Atlantic and the Mediterranean regions. But the evidence 

 of its great regularity is almost peculiar to western America. 



It is important to know upon what basis a given fauna is 

 assigned to a certain horizon, and also what genera or species 

 are used as climatic criteria. Not all genera or species are 

 equally characteristic, nor are they equally characteristic in 

 different geographic zones. Cucullcsa is an Eocene genus in 



