THE FULUS TERRESTRIS. 421 
measured about a line in length, and exhibited the nine original 
segments, the first seven being strongly marked. In the space 
we have called the antepenultimate, six new segments were now 
developed; these were still very small, the length of the whole 
being equal to that of one of the others. At that time they 
did not form independent divisions of the body, but were covered 
by the common skin or tegument. The last segment of the body 
and the penultimate are permanent, and are not divided off into 
the segments which make their appearance from time to time, 
and these are really new growths. 
The skin covering the whole body is thrown off, and then the 
Fulus appears with the six new segments mentioned above, and 
ready for food. It will be observed that additional legs have 
begun to grow. Hitherto the Fu/uws has had three pairs, but four 
additional pairs are in course of formation, and they exist at this 
period as nipple-shaped prominences on the under surface of the 
sixth and seventh segments, four on each, and covered by the 
common skin or tegument which is beginning to fall off. The 
three pairs of legs that now exist are attached as follows :—One 
pair to the prothorax or second segment, one to the third, and 
one to the fifth segment. The general appearance of the animal 
has now become less delicate, the head has acquired a darker 
colour, and a faint broad patch is making its appearance at the 
anterior part of the seventh segment. This patch (Figs. 5, 6, 7) 
is permanent through all the earlier changes, and is of the greatest 
utility in determining how new segments are produced. Such was 
the condition of the young ¥wdws an hour after leaving the mem- 
branes. It soon began to exhibit its animal powers, to show the 
instincts peculiar to its species, and to be sensibly affected by 
external causes. In less than six hours the little creature was 
in motion. At first the antenne were the organs employed, 
and they were moved slowly to and fro, and appeared to gain 
power by use. In a short time the limbs began to be extended, 
and the animal slowly raised itself upon them for the first time. 
Its first efforts at locomotion were exceedingly feeble, but it 
gradually gained strength. At the end of twelve hours the Falus 
crawled about slowly, but moved its antenne briskly. On ex- 
posing the insect to a strong light, a marked effect was produced 
