6 J. C. BRANNER 
the Coyote at the summit of the watershed would, in this fashion, 
afford an opportunity for the mingling of the fauna of the Pajaro 
and its tributaries with that of Coyote Creek and its tributaries. 
Fishes from the Pajaro could ascend the stream into the mountains 
while the water flowed toward the Pajaro, and when the stream 
shifted, or its waters divided, these fish could descend the Coyote. * 
But the problem of the mingling of the fish faunas is not confined 
to the Pajaro and Coyote alone; it extends to the Sacramento and 
other streams flowing into the Bay of San Francisco and to other 
streams flowing into the Bay of Monterey. So long as the Bay of 
San Francisco is filled with salt or brackish water it is an effective 
barrier against the passage of these fishes. 
The additional requirements of the case seem to be met by the 
theory of a former elevation of the coast. Indeed, not only does 
such a theory afford a satisfactory explanation of the mingling of 
the fish faunas of the streams under consideration, but it is necessary 
for the explanation of other phenomena more or less directly con- 
nected with this subject. That there was such an elevation is shown 
not only by (1) the mingling of the fish faunas of the streams referred 
to, and which I am unable to account for in any other way; but also 
by (2) the greater activity of the streams of the coast at a period not 
far removed geologically; by (3) the submerged valleys along the 
coast; and by (4) the islands off the California coast. 
It is not proposed to discuss these evidences at length, but a few 
words may be said of the importance of each one. ‘The evidence 
of greater activity of the streams is not confined to the Coyote or to 
the streams of any particular district, but it is common to the streams 
of the Coast Range and of the Sierra Nevada. The great alluvial 
cones of the glacial epoch are far beyond the reach of the modern 
1 The topographic peculiarity here cited is not unique. In 1892 Dr. B. W. Ever- 
man, in connection with the work of the U. S. Fish Commission, pointed out how fish 
may cross over the continental divide from the Columbia River basin to the Mississippi 
basin by way of Two-Ocean Pass. There isa similar low alluvial fan in a meadow on the 
watershed between the drainage of the Paraguay and of the Amazon basin. In 
both of these cases the watersheds permit the mingling of the existing fauna. (The 
Report of the Commissioner of Fish and Fisheries respecting the Establishment of 
Fish Cultural Stations in the Rocky Mountain Region and Gulf States, Miscellaneous 
Senate Document, No. 65, pp. 22-26 [Washington, 1892].) 
