378 



BULLETIN OF THE BUREAU OF FISHERIES. 



No important differences have been detected between the fishes of the streams entering 

 Tomales Bay and those of Russian River or the Sacramento. There is then no zoological 

 evidence to offer concerning the origin of the Tomales Bay fauna further than that it was 

 probably derived from either the Russian River Basin or from some stream tributary to 

 San Pablo Bay, for it will be observed from the map that the catchment basin of Tomales 

 Bay is bounded on the north and east by the territory drained by Russian River and the 



Map of Tomales Bay, showing tributary streams large enough to support fishes. 



small creeks which flow into San Pablo Bay." Furthermore, it is separated from rivers 



farther up the coast by a barrier of sea water which can not be traversed by fluvial 



species. 



SYSTEMATIC DISCUSSION. 



Catostomus occidentalis Ayres. Sacramento sucker. 



This species was observed in Olima and Papermill Creeks but not in Walker Creek. Specimens 

 have been collected in Olima Creek at its mouth. On the 20th of October and on the following day, 



" Of interest in this connection is a paper by Prof. Ruliff S. Holway ; The Russian River, a characteristic stream of the 

 California coast ranges. University of California publication, in Geography, vol. I, no. i", Apr. 8, 1913. 



