History of British Entomostraca. 317 
than twenty days, andin a series of very careful experiments whichhe 
made in February and March, he found it to occupy twenty-eight 
days. For the first eight days, they underwent little or no change 
between the eighth and thirteenth the body appeared a little more 
elongated between the thirteenth and nineteenth, the line of demar- 
cation between this increase of length and primitive size was trace- 
able by a line of a brown colour, and the insect had acquired a third 
pair of feet between the nineteenth and twenty-fifth, no great change 
took place, only the third pair of feet were more developed between 
the twenty-fifth and twenty-eighth the first moulting took place 
and thirteen days afterwards they moulted a second time. In a 
series of experiments which I undertook, upon the same species, in 
the end of June and beginning of July, when the thermometer was 
frequently above 80 during the day, I found the time occupied in 
the process, in some instances, very much shortened. In one brood 
which were hatched on the 21st of June, I found some had com- 
pleted their first moulting on the 1st of July, or on the eleventh day. 
In another brood hatched on 22d June, I found the same result, se- 
veral of the young having undergone a first moulting on the 2d July. 
On the 4th I could only see one that had not moulted and next 
day, the 5th, this one had also undergone the change : the second 
moulting in many of them took place only a few days after the first. 
In another brood hatched a little earlier in June when the weather 
was not so hot, I found the changes take place as follows : When hatch- 
ed the insect appeared of an oval shape, (Plate VIII. Fig. 9,) having 
two thick antennae of three articulations each; two pairs of feet, bifid 
at extremity ; in the upper pair, one division consisting of two and the 
other of only one articulation; in the lower, both divisions having only 
one articulation ; extremity of body furnished with two short setae on 
each side. On the eighth day, the body is considerably elongated, and 
a distinction has begun to be perceptible between this increase and 
original si8e,with some appearance of setae where thethirdpair of feet 
afterwards appear ; intestine very distinct, (Fig. 10.) On the fif- 
teenth day, the third pair of feet have become distinctly formed ; the 
lower part of body more elongated, the elongation marked by an- 
other line of demarcation ; the setae on the edges of the antennae have 
become visible, and those of the feet longer and more numerous, 
whilst the second pair of feet have the upper division of two articu- 
lations, (Fig. 11.) On the seventeenth day, moulting has taken 
place the body is divided into two segments ; tail into three ; the 
terminating one cleft at extremity, each cleft sending off a long seta; 
antennae of about six articulations ; the antennules have become dis- 
tinctly visible, and the feet have assumed the appearance they after- 
