72 MR. J. LUBBOCK ON THE DEVELOPMENT OF 
In the antenne, however, the new segments appeared to me to be always detached 
from the apical extremity of the third segment itself; in the tails, on the contrary, the 
young segments again subdivided,—a difference connected perhaps with the much more 
rapid increase of length. Only a few, however, subdivide at each moult: thus, the 
number, which in the last stage was seventeen, is now twenty; the consequences are 
that the length of these segments does not increase so regularly as is the case with the 
growing part of the antenna, and that the circles of spines round the apices are of 
different sizes, being of unequal age. The two basal segments appear generally to divide, 
so that the spines at the apices of the second and fourth segments are larger than those 
on the first and third. In some specimens, however, the two tails differ slightly in this 
respect. The fringe now commences on the eighth segment, which, with the three 
following, has a single hair on the inner side; the next two or three have each two hairs, 
then follow two or three with three, after which they again decrease. "They are confined 
to the developing part of the tail, and are independent of, and in addition to, the : 
ordinary apical setze. 
The central tail is now 325ths in length, and consists of two or three, but indistinctly 
separated, segments. It is stout in proportion to its length, and terminates in a rounded, 
soft extremity, very much as the lateral tails do if by any accident they have been 
injured. This mode of termination is not, however, in the present case the result of 
injury, but is probably connected with the rapid growth which is taking place. 
Seventh State (fig. 7). 
The sixth state does not last much longer than the earlier ones. In my specimens, the 
next moult took place when the insects were from 335ths to 4% ths in length. 
The antennz are about 6 ths, and consist of twenty segments, the third having again 
divided into three. 
The supporting spines on the tarsi have again increased in number. 
Up to this time the branchie have been single, and, indeed, they are so still; but the 
larger ones already show on the posterior margin a slight lobe, which eventually becomes 
a second plate (Pl. XVIII. fig. 22). 
The lateral tails are slightly longer than the body, and consist of thirty-two segments. 
The hairs forming the commencement of the fringe are rather more numerous. The 
terminal portion of the tail is unaltered. 
The middle tail is from 535ths to +43 ths in length, and consists of about six segments, 
one or two of which, however, are sometimes very indistinct. 
Eighth State (fig. 8). 
The insect moults again in about three days, when it has a length of from zf5ths 
to حيتي‎ 
In a specimen #5 ths in length, the antennee were zths in length. They consist of 
twenty-three segments, the third having divided into four; the penultimate segment has 
been becoming a little shorter at each moult. 
The secondary lobe of the branchize is larger and more distinct. 
