276 MR. F. BALFOUR-BROWNE ON THE [ Mar. 2, 
longer than in the ‘6-segmented” condition. The average 
length of the “7-segmented ” antenne is also greater than that 
Chart showing the growth of the segments of the antennex in Agrion pulchellwin Lind, 
of the ‘‘6-segmented” antenne for the same stage, indicating 
that the larger nymphs of the stage are those which are near 
their final ecdysis. 
THe LAMELL2. 
Like the antenne, the lamellz are much longer in proportion 
to the body-length in the newly-hatched nymph than in the full- 
grown one. Whereas they are almost the same length as a 
nymph of 1°3 mm., in a nymph of 17 mm. they are less than 
half the length. 
The pointed linear organs of the first-stage nymph gradually 
widen out in the vertical plane and ultimately become leaf-like. 
In both Agrion pulchellum and puella, and perhaps in all species 
of this genus, they gradually lose their pointed appearance and 
become distinctly rounded at the apex. Not only have I observed 
this rounded character in nymphs reared from the ege, but I 
have repeatedly hatched out the imagines of both these species, 
and only those nymphs with rounded lamelle produced Agrions. 
I mention this because Lucas (1900, pp. 281, 288) describes the 
lamellee of A. puella as being always pointed, and says that those of 
A. pulchellum are appar ently similar. He mentions, however, that 
some authors have described them as having rounded apices. The 
full-grown nymph with pointed lamelle, which is otherwise almost 
(or quite 2) indisting wishable from the Agrions, is [schnura elegans. 
