50 
BRITISH ENTOMOSTRACA. 
ovary opening at the point, and the eggs being thrown 
out by a sudden jerk, to the number of ten or twelve, very 
rapidly. The whole process of laying lasts several hours, 
sometimes, according to Prevost, for a whole day, and 
the number of ova excluded vary from 1 to 400. At 
first the egg is yellowish, spherical (t. V, f. 1), and in- 
closed in a thick, hard envelope, beset all round with short 
setae, but when it has been for a short time exposed to the 
action of the air and water, it assumes an irregular 
hexagonal figure, and a greenish hue. In about a fortnight 
or so, the egg is hatched, and the young one issues forth, 
but very unlike its parent. It consists of two nearly equal 
oval portions, head and body. 
The cephalic division possesses two very large antennae, 
and two pairs of largely-developed natatory feet, the an- 
terior much larger than the others, and both furnished 
with a considerable number of stiff setae springing from 
their under edge. 
The eye is sessile, not compound, a single black spot, 
situate in the middle of the fore part of the head, between 
the antennae. There is at this time no appearance of the 
pedunculated eyes, and it would seem that these require 
considerable elaboration to come to perfection. In the 
adult state, upon dissection we see these eyes furnished 
with well- developed muscles and nerves, while there is 
no trace remaining of any muscles, or vessels of any kind, 
going to the black spot, the mark of which then still 
remains. 
In a short time after birth (longer or shorter accord- 
ing to the temperature), the young creature throws off 
its skin, or moults, and we then see a distinct appear- 
ance of the two lateral eyes ; the body becomes much 
increased in size, is divided into segments, and a series 
of knobs or projections may be observed along its edges, 
destined to become the feet, while at its extremity we see 
a notch, with a filament from either side, being an ap- 
proach to the formation of the tail. It soon moults a 
second time, and we then see the buds, as it were* of the 
