15 



much more could be learned concerning the habits which are at 

 present unknown. 



The lii-st shrimp were caughl this year m the Latter pari of 

 March. All were small and sexually undeveloped. No largo 

 individuals were caught until much later m the season. At this 

 time the gonads (reproductive organs) were wry small and in- 

 conspicuous, in fad being ra'ther hard to find. Bui little change 

 in the size of the individuals or in the condition ol the gonads 

 was found until the latter part of April. At this time the catch 

 had shown ;i gradual Increase in size although small individuals 

 were still rather common. At this time the males began to show 

 signs of approaching maturity, as evidenced by the increase in 

 the size of the lestrs and by the terminal portion of the sperm 

 duct (in the basal segment of the last pair of legs) becoming 

 conspicuously white. During the following month the relative 

 number of matured males continued to increase nidi I by the latter 

 part of May practically all the males caughl were wild mature 

 elands. None of these, however, were above medium size and 

 large-sized individuals were not caught until rater late in the 

 summer. 



Although many females were caughl at the same time, the 

 increase in the size of the ovary was not as conspicuous and in 

 noii,. of the specimens caughl were there any which indicated 

 thai the ovary had attained full size. 



In the latter part of May the shrimp were driven from the 

 Vasx by the heavy spring freshet. The heavy freshets this past 

 spring were extremely troublesome and caused a greal deal of 

 damage. 



As other duties required my absence from the Station for the 

 next two months, no observations were made until the latter part 

 of -luly. A1 this time shrimp were again fairly common in the 

 Pass, hut none of Hum showed any signs of sexual maturity 

 In fact, in every case examined, all seemed to have returned to 

 the same stage of development as that found in the specimens 

 caught in the early spring. During the latter part of August 

 and during September the shrimp were exceedingly numerous at 

 times and records were kept with a fair amount of regularity 

 During this period they were growing rapidly and the majority 

 of specimens captured had either recently moulted or were about 



