332 REPORT UNITED STATES ENTOMOLOGICAL COMMISSION. 
as in Agrion ; those of the metaplcurum are much as in the meso-, but 
a well-marked suture separates the meso-epimerum from the meta-epi- 
sternum, and the latter is much wider towards the insertion of the wing 
than next to the coxa. 
In the prothorax of iEsclma the episternum is very small, and sub- 
divided into several pieces; the epimerum is larger and not divided; it 
is about as long as broad, and posteriorly submembranous. 
The coxa is very large, being much enlarged within, meeting the 
opposite coxa on the median line. 
Menopleurum (Fig. 1) enormous, and forming a large part of the dor- 
sal region of the thorax. The episternum is enormous, forming with 
its fellow on the opposite side a large proportion of the front and meso- 
notum; the foramen leading into the prothorax is situated very low, 
the mesostigmata being situated on the upper side of the opening. 
The two meso-episterna unite to form the front of the mesothorax and 
also the anterior fourth or third of the dorsal region of the entire thorax. 
Dorsally there is on the united episterna a high median ridge becom- 
ing forked behind, with two lateral diverging transverse ridges. The 
ridge originates in front from the hinder border of a transverse cres- 
cent-shaped area directly above the foramen leading into the pro- 
thorax. A straight, distinct suture separates the episternum from the 
epimerum. Between the episternum and the trochantine is a sclerite, the 
nature of which is uncertain; by its close relation to the sternum it may 
be the infra-episternum and probably not the coxa, the latter appearing 
to be obsolete. 
The epimerum is large, broad, oblique, and below in front of the meta- 
stigma separated by suture from the meta-episternum, but above there 
is no suture, only a broad, valley-like depression. 
Metapleurum. The episternum is about one-half as wide as the large, 
swollen, smooth epimerum, which composes the posterior third of the 
pleurum of the thorax. Below the metastigma is a square sclerite, 
directly over the trochantine, which is probably the infra-episternum, 
there apparently being no coxa; the trochantine as in the prothorax. 
Sternvm. 
In Agrion the prosternum is small, triangular, longer than broad, 
with the apex acute. 
Mesosternum a little larger and broader than the prosternum, but 
still small. 
Metasternum. A hat I am disposed to regard as this sclerite is a very 
large, elongated, polygonal area, which is semi-membranous and flat. 
In Calopteryx the sternites are as in Agrion, but the metasternum is 
broader and shorter, with an anterior deeply impressed median line. 
In JEschna the mesosternum is small, broad, irregular; while the 
metasteruum is much smaller, nearly obsolete in front of the legs, 
