MliRKlAM. 



On Two Tertiary Faunas. 



applied to west coast geology, even when the number of species at 

 hand is large, it may be stated that, while it is certainly of great 

 value where once standardized, it is doubtful whether the percent- 

 ages of Recent molluscan species found in the faunas of the different 

 Tertiary periods in other parts of the world would correspond at all 

 to the percentages of modern forms, which existed on the west 

 coast during the same periods. Corresponding to variations, or 

 lack of variation, in topography and climatic conditions, the average 

 percentage of Recent species on the west coast in any given period 

 may have been much larger or much smaller than elsewhere. 



Comparing the Sooke fauna with that of well-known Tertiary 

 and post-Tertiary horizons of the Pacific Coast, we find that six or 

 seven of the species are known from the Miocene and about an 

 equal number from the Pliocene, nine species are found in the Qua- 

 ternary and Recent, and seven or eight are not known to occur 

 elsewhere, either recent or fossil. 



The fauna of the Sooke beds, as represented in Dr. Newcombe's 

 collection, is quite different from any of the Oregon or California 

 Miocene or Pliocene faunas known to the writer. The presence of 

 such a large percentage of new forms, and the decided difference of 

 the whole fauna from that of Carmanah Point, of Astoria and of the 

 lower Pliocene of Northern California, are rather surprising when 

 we take into consideration the relation of these faunas to each 

 other. There are common to the Carmanah Point and Sooke beds 

 about five species; two good and three doubtful. This is a much 

 smaller number than we should expect to find if both horizons 

 belong to the Miocene or even if one were lower Miocene and the 

 other lower Pliocene. This may be explained either by supposing 

 the interval between the deposition of the original sediments con- 

 taining the Carmanah Point fauna and the deposition of the Sooke 

 beds to have been a very long one, allowing time for radical faunal 

 changes, or by supposing considerable topographic and climatic 

 changes to have taken place in a shorter interval, accompanied by 

 immigration of new forms. 



Supposing the Carmanah Point and Sooke faunas to have lived 

 at different periods along the shore of the same ocean, we can hardly 

 suppose the latter derived from the Carmanah Point fauna by 



