212 
BULLETIN OP THE BUREAU OF FISHEBIES 
native oysters. Those moved north from Virginia spawn later than the 
native strain. 
The critical temperature for the razor clam of Alaska is probably not lower 
than for those on the Washington beach, as the slight difference in summer tem- 
perature probably insures an opportunity for spawning along the whole coast 
under similar conditions. The temperature of the inshore waters, from Pismo, 
Calif, (the southern limit of Siliqua patula), to the end of the Alaskan Peninsula, 
is quite uniform during the summer. 
Jsn. Apr July Oct. Jan. 
Fig. 9. — Showing the mean (average) monthly temperatures for Washington beach and ICetchl- 
kan (Ketchikan temperatures furnished by U. S. Coast and Geodetic Survey). # — #, Wash- 
ington beach ; o — O , Ketchikan 
The temperature record for Ketchikan is the only complete set for Alaskan 
waters. Comparison of these with records taken over the clam beds indicate that 
they are representative of conditions that exist generally over the whole region. 
The more southern waters reach what might be called a normal temperature 
earlier than do those farther north, and they also cool later in the year. For 
instance, the Washington temperature was above 13° C. for twice as long as was 
the temperature at Ketchikan during the 1923 season. (See fig. 9.) The mean 
temperature for each month showed a difference in the maxima of 1.8° C, while 
