ORDER BRANCH [OPODA. 
345 
their intercourse, which lasts, at most, from eight to .ten 
minutes. The male, placed at first on the back of the female, 
seizes her with the long filaments of his anterior feet ; then 
getting towards the inferior edge of her shell, and approximat- 
ing his own to its aperture, he there introduces these fila- 
ments, as well as the hooks or harpoons of those feet; he 
then approaches his- tail to that of his companion, who at 
first rejects his addresses, runs with great swiftness, carry- 
ing him along with her, but ends by yielding. Some small 
bodies, in the form of grains, of a green, rose, or brown colour, 
according to the seasons, composing the ovaries, ascend 
gradually into the matrix, and there become eggs. Jurine 
observes, that the males of the D. Pulex are of small num- 
ber, in comparison with the females, that in spring and 
summer hardly any are to be found, but that they are less 
rare in autumn. 
About eight days after their birth, the young daphnise 
change their skin for the first time, and subsequently continue 
the same operation every five or six days, according to the 
greater or less elevation of temperature ; not only the body 
and the valves, but also the gills and the seta) of the oars, are 
stripped of their epidermis. It is not until the third moulting, 
that these Crustacea begin to reproduce ; they at first lay but 
a single egg, then two or three, and increase progressively, 
even up to fifty-eight in one species, (l). Magna). In a 
single day after the laying, the female changes skin, and in 
the teguments which she has abandoned, are found the shells 
of the last laid eggs. In a moment afterwards she lays again. 
The young of one and the same birth, are almost always of the 
same sex, and it is rare to find in a birth of females, two or 
three males, and vice versa. But in five or six births during 
the summer months, one at the most, consisting of males, 
takes place. Individuals are often to be met with, whose 
teguments are of a milky white, opake and thick, without the 
