498 



THE AMERICAN NATURALIST [Vol. LI 



larvae and pupae are at all times of the year present in the lake, 

 though less abundant in winter. In the winter months there are 

 but few in the open water, but they are common in the debris 

 above mentioned. Dates for first appearance of adults were not 

 secured, though some appear as early as April ; they become com- 

 mon by June, and in July and August are so exceedingly numer- 

 ous as to be a serious nuisance at times about Saltair pavilion, 

 wind conditions being apparently a determining factor in their 

 coming in swarms about the bathhouses. Ordinarily they keep 

 below the level of the floors, on the piles and on the water sur- 

 face. Whether any eggs survive the winter can not be stated. 

 There is no evidence of the pup^e surviving on shore, where 

 thrown up by the waves. It seems likely that larvae and pupae 

 which remain submerged are the principal, if not the sole means 

 of surviving the winter period. 



Adult Artemias, the females with fully developed egg sacs, are 

 very plentiful throughout the summer and fall into October. In 

 this month the temperature of the water falls from the summer 

 temperatures of between 25° and 30° C. (exact summer maxi- 

 mum unknown to writer) to as low as 15°-18° C. In November 

 with the temperature as low as 6° C. there may still be seen 

 some few adults. At a December temperature of 1° C. and 

 lower (doubtless goes lower at times for short periods) no adults 

 can be found, as a rule, though reported by Talmage. An abun- 

 dance of eggs can be secured in fall, winter and spring, especially 

 in the debris near shore. Possibly some may settle into the 

 smooth oolithic sand of the open lake bottom, but I have no evi- 

 dence that such is the case, and the eggs tend rather to float than 

 to sink. Young appear in April and May, abundantly in the 

 latter month. The earliest record secured for young was March 

 12 (1910), when a number of minute young were taken. The 

 temperature at that time was 9° C. It will be noticed that Ar- 

 temm differs markedly in its long season of activity from its 

 fresh-water cousin, BrancMpus, which is so soon gone from its 

 evanescent breeding pools. Correlated with this long active 

 period is the continued presence of abundant water and food 



