History of British Entomostraca. 407 



pregnant. February ] , young born. On the 5th December, isolat- 

 ed a young Daphnia born from an ephippium. January 18, it has 

 given birth to young. 19th, isolated two of these, both females. 

 February 8., both of these have given birth to young. Isolated two 

 of them. I was at this period obliged, from circumstances, to sus- 

 pend my observations ; but the above experiment is sufficient to 

 prove the fact, that the young born from an ephippial egg produce 

 young, which in their turn become mothers without the interven- 

 tion of the male. 



According to Jurine, who has watched the act with great care, 

 the following is the manner in which copulation is effected : — 

 When the male attacks the female for this purpose, he springs up- 

 on her back, and gradually descends till he reach the inferior edge 

 of her shell, and finds himself in a position where the open edges 

 of the shells are opposed to each other. He then introduces the 

 " harpons" and " filets" of his first pair of feet into the interior of 

 her shell, and with them embraces her feet. Thus fixed, he then 

 curves up his tail so as to touch the female, who at first is much agi- 

 tated, but after a little time pushes out her tail also. They touch 

 each other, and then the Daphniee immediately separate, the male 

 at the time of touching having been agitated with convulsive mo- 

 tions. The eggs are first to be seen in the shape of small round 

 pellucid globules, which mark the situation of the ovaries placed 

 along the sides of the intestine. These soon lose their transparency, 

 become enlarged and continuous, and form a dark mass on the outer 

 edge of the intestine, partly globular and partly elongated. The insect 

 now changes its skin, and shortly after the eggs quit the ovary by the 

 communication to be hereafter mentioned, and take their place in a 

 spherical form in the open space on the back of the insect, where 

 they remain till the time of expulsion quite free and unattached. 

 At first they are quite round, and appear to consist internally of lit- 

 tle globules like air globules. The shape then alters a little, be- 

 coming oval, and the globules augment in number, but as yet no 

 trace of any part of the body is recognizable. A little afterwards 

 we see a black spot in the centre, which is the eye, and which is the 

 first organ visible. The other organs then begin to shew them- 

 selves, but it is not till near the end of the fourth day, or the ninetieth 

 hour after laying, according to Straus, that motion is perceptible. 

 At the end of the fifth day, according to the same author, they are 

 launched into open day. They are from the first exactly like the pa- 

 rent insect, undergoing no metamorphosis, but merely differing in 

 the less complete development of parts. In the D. pulex, the 



