484 SIR J. LUBBOCK ON THE DEVELOPMENT 
fringes ; but the whole surface is covered with short, equidistant, strong, pointed hair, 
The middle tail of the larva is represented by a short conical appendage. 
The sexual appendages of the male (Plate LIX. fig. 14) are four-jointed. The two 
basal segments are short and broad; the third is cylindrical, =; of an inch in length. 
The terminal segment is small. The whole organ is covered with minute hairs. These 
organs are absent in the female. 
Imago. 
The two great pillared eyes (Plate LIX. fig. 15) at once distinguish the male from the 
female. In the latter they are entirely absent: in the former they occupy almost the 
whole top of the head; and the larval eyes, which do not appear to have undergone any 
great change in appearance, are thrown entirely to the side. The pillared eyes are 
facetted only on the flat summits. The antennæ resemble those of the proimago. 
The anterior legs of the male (Plate LIX. fig. 16) are elongated, though not so much so 
as in some other species. The tarsal segments, which are four in number, decrease in 
length from the first to the last, which bears a single claw. The two posterior pairs 
more closely resemble those of the proimago, and, like them, have the third segment 
shorter than the terminal one. The third pair terminates in a pad and a claw (Plate LIX, 
fig. 17). The skin of the legs resembles that of the proimago. 
The wings are paler and more delicate than those of the proimago. There are no 
hairs, nor is there any fringe on the hinder margin (Plate LIX. fig. 18); but the nervures 
are more sharply defined. The shape of the wings and the arrangement of the nervures 
has undergone little change. f 
It is difficult to understand the cause of the differences which exist between the wings 
of the proimago and those of the imago. They are not confined to this species, but 
appear to be general to the whole group. In Palingenia virgo, indeed, the posterior 
margin bears a row of hairs; but even in this species they are quite unlike those of the 
proimago. 
The two tails are of considerable length, and consist of a number of segments. re 
are near the base, about 346 of an inch in thickness, and each segment has a length 0 
from 135 to 135 of an inch. Instead of the long fringes which were present in the larv®, 
and which may be supposed to have been of assistance in swimming, the whole er 
of the caudal appendages in the imago is covered with short, stiff, pointed hairs, whic 
are all of nearly the same size. 
. The appendages are pale in colour; but the joints are dark brown, which gives them ? 
ringed appearance. Sometimes every second joint is darker than the rest. 
The perfect insect makes its appearance in June, 
In my previous memoir I referred the above insect, on the authority of Mr. bs 
to Chloéon dimidiatum. Since then I have also forwarded specimens to Mr. M‘Lae the 
who has devoted much time to the examination of this family, and who confirms 
opinion of Mr. Walker. The group, however, much wants a careful revision. Ee 
Curtis's description of Chloéon dimidiatum is as follows :—* Length 3 lines. ici 2 
brown; collar with an ochreous dot on each side; abdomen, especially at the 9% 
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