10 G. C. Embody. 



hold during the ecdysis of the female but regains it soon after the 

 female has emerged. The pair continue together until copulation has 

 taken place. After this act, in all cases which came to my notice, the 

 male separated from the female permanently or at least until he had 

 moulted once. 



Miss Clara Langenbeck (1898, p. 305) foimd practically the same 

 state of affairs obtaining among amphipods of the genus, Micro- 

 deutopus. Accordiug to her observations the male's second separation 

 from the female occurred shortly before the extrusion of the eggs. 



Dr. S. J. Holmes states (1903, p. 288) with reference to the ob- 

 servations of A. Delia Valle on Gammarus pungens that after the 

 act of copulation, the male regains his original position and swims 

 about with the female as before. 



Frequent captures of mated females of the three species, G. fas- 

 ciatus, G. limnaeus and Hyalella with pouches full of eggs or 

 young led the writer at first to believe that the males remained with 

 the females for a number of days after oviposition and even after the 

 eggs had hatched. In every ease tested however, it was found that 

 the male was to become father of the next succeeding brood; and 

 furthermore, inability to secure two successive matings of the same 

 male during the period between two moults convinced me that these 

 males were not responsible for the eggs or young present in the pouches 

 at the time of collection. 



3. Oviposition and Fertilization. 



Oviposition and fertilization have been observed by A. Delia Valle 

 for Gammarus pulex (1889) and for Microdeutopus gryllotalpa 

 by Miss Langenbeck (1898, p. 305). According to the observations of 

 the former as abstracted in the "Zoological Record", the oviducts have 

 ordinarily no external apertures. Oviposition is preceded by a casting 

 of the integument whereby external openings are temporarily formed. 

 FertiHzation is quite external, no intromittent organs being employed. 

 The sperm is ejected upon the ventral surface of the female round the 

 terminations of the oviducts. The eggs issue simultaneously by the 

 two oviducts, and are accompained by a viscid substance which plugs 



the head and the first dorsal plate, the male placed one gnathopod through the slit 

 and inserted the dactylus in the usual place on the female. In this manner his hold 

 was retained with difficulty until the female emerged free, when the usual firm hold 

 was obtained. 



