1921] Schmitt: The Marine Decapod Crustacea of California 291 
Current ‘‘it really is the part of the Japan Stream bordering the 
Pacific Coast, and doubtless would not have been given a different 
name were it not for its low temperature and relatively greater 
velocity.’’ (McEwen, 1915, p. 183.) 
It is these two great, as it were compensating influences, the one 
warming a northern, normally cold region, and the other cooling a 
southern, normally warm region, which tend to equalize the tempera- 
tures along the greater part of the west coast and to make possible 
the large faunal area which extends from about the eastern Aleutian 
Islands to near Magdalena Bay, Lower California. 
These conditions are graphically portrayed, in a general way, in 
Berghaus’s Physical Atlas (1892, pls. 21 and 22, ‘‘Seestromungen’’), 
but our present detailed knowledge concerning them is almost entirely 
due to the researches conducted by Dr. G. F. McEwen under the 
auspices of the Scripps Institution (1910, 1912, 1915, 1916). 
A number of students of the west coast fauna, chiefly conchol- 
ogists (Dall, 1899, 1909, 1916, and Bartsch, 1912, also Torrey and 
Verrill above), attach great importance to Point Conception as a 
faunal barrier. Possibly their conclusions are influenced by a pre- 
dominance of littoral (sensu strictw), or shallow-water forms. These, 
especially in the case of mollusks, always reflect extremely localized 
environments, and were they excluded and only those of less restricted 
(bathymetric) range considered, i.e., 25 to 50 to 100 fathoms, no 
doubt Point Conception as an apparent faunal barrier would cease to 
be significant. Of the California decapods, only twenty-eight (15%) 
are at present restricted to the region north of Point Conception and 
winter. Also, it appears that the annual range of off-shore temperatures agrees 
with the normal range for the same latitude. But the inshore temperatures are 
notably less than the others for the same latitude, especially during the warmest 
part of the year, and consequently have less than the annual normal range. Again, 
the maximum and minimum temperatures occur in-shore some months after the 
corresponding normal times; and the variation of in-shore temperatures. with 
respect to the latitude is scarcely half the normal amount.’’ (McEwen, 1915, 
p. 134.) 
SuRFACE TEMPERATURES AT LATITUDE 30, 150 Mines SourH or San Disco 
Average ocean temper- Temperature of the Pa- Temperature of the in- 
atures for the whole cific at the houndary shore water along 
circle having the giv- of the California and the Pacific coast. 
en latitude. Japan currents. 
Time of Time of Time of 
Temp. occurrence Temp. occurrence Temp. occurrence 
eS ote ay viet eee 77°. August 72° Aug., Sept. 65° September 
Mamimumyse 64° February Gls April 59° May 
Annualrange.... 13° inl 6° 
SURFACE TEMPERATURES AT LATITUDE 40°, OFF CAPE MENDOCINO 
Maximum .......... . 66° August 66° September 57° October 
Wiliotorat pied e eee eee 48° February 51° ~—s- April 52° March 
Annual range... 18° 15° 5° 
