NOTES ON THE LIFE HISTORY OF GAMMARUS CHEVREUXI. 551 



About an hour and a quarter after the moulting the male began to 

 turn the female round, and after several efforts he succeeded in getting 

 into the position described by Delia Valle. At 8.30 p.m. the first 

 ejection of sperm into the pouch was eflected in four or five spasmodic 

 movements. After lying quiet in this position for a minute or so, the 

 male resumed the dorsal clasp, but five minutes later the whole 

 process was repeated. Once more after an interval the male resumed 

 the original dorsal position and swam again. After another five 

 minutes — at 8.40 p.m. — the female suddenly struggled free, and did 

 not allow the male to carry her again, darting away if he approached. 

 Just at the moment they separated the first egg was seen emerging 

 from the aperture of the oviduct. The last egg passed from the 

 ovaries exactly twenty-four minutes later, and the newly extruded 

 mass hung in the pouch in spheroidal form, the eggs held together by 

 a glutinous secretion. The number of eggs was forty. 



In another case watched, a distinct oviduct was apparent during the 

 passage of each egg from the ovary to the exterior. This v/as clearly 

 distinguishable as a thin light line only during the actual extrusion of 

 the egg. The eggs laid first were pushed forward in the pouch by tlie 

 later ones, and it may be mentioned here that the front ones were seen 

 to hatch first. 



The female can moult alone after extruding a brood from the pouch, 

 so the presence of a male is not imperative for the moult, but our 

 experience agrees with Embody's, that eggs are never deposited unless 

 a male is present. In the absence of a male the eggs develop enor- 

 mously in the ovaries, and are separated by distinct spaces, as happens 

 during the normal development in the pouch, but what ultimately 

 becomes of them has not yet been traced. 



We have tried several experiments to determine the extreme interval 

 that can elapse between any given moult and the subsequent oviposi- 

 tion, and we find that on the third day oviposition is still possible. If 

 a male is kept away for four days or more after the female's moult, 

 no mating occurs until the fourteenth day, i.e. until the next period 

 begins, and such mating is preceded by a second moult. 



It is evident that in the female moulting is directly connected with 

 mating. The animal of course increases in size also, but as the moults 

 occur at fortnightly intervals this increase is too gradual to be 

 noticed at the time. With the male, on the contrary, moulting appears 

 to be purely a growth process. The moults are at long intervals, and 

 the increase in size very noticealde. The oldest male we have, 

 extruded June 19th, became sexually mature July 25th, and has only 

 been observed to moult three times since, on Aug. 1, Sept. 4, and Nov. 5. 



