330 REPORT UNITED STATES ENTOMOLOGICAL COMMISSION. 
vertex. As the eyes are enormous and meot on the median line of the 
head, the epicraniuin is divided by them into three portions: 1, a nar- 
row orbito-gular area, not soon from above; 2, an ocello-antennal, very 
small, subtriangular area; and 3, a pre-anteuual, large area, correspond- 
ing to the small ante-antouual area in Agrion. This area, with the 
clypeus, forms the peculiar sholf-lilco projection of the front of the head. 
The area is divided into a horizontal broad area and a transverse cres- 
cent-shaped subarea, separated from the horizontal portion by a sharp 
ridge. The clypeus is very large and full, reaching from eye to eye, 
and nearly as long as broad. It is separated from the epicraniuin by a 
well-marked curvilinear suture. In front it incloses the ante- clypeus, 
which is a crescent-shaped sclcrite no wider than the labrum, and sep- 
arated by a distinct suture from the clypeus proper. 
The labrum is large and broad, very distinct from the clypeus. 
THE THORAX. 
No turn. 
The Odonata are characterized by the unusual development of the 
pleurites, the meso-epistornum forming the largor part of the dorsum 
of the thorax, the meso- and metanotum being greatly reduced in size, 
^ owing to the great and long-sustained powers of flight possessed by 
these insects. 
In Agrion the pronotum (PI. XLYII, fig. 10) is well developed com- 
pared with the meso- and metanotum; somewhat broader than long, 
divided into three areas, being emarginate in front and behind, with the 
edges turned up, while the large central area has two lateral, slightly 
swollen areas. 
Mesonotum. (Fig. 11.) The praescutum not visible; scutum entire, 
minute, not much longer than wide. The scutellum is a much swollen 
rounded knob, with the base subtriangular, not much smaller than the 
scutum. The post scutellum appears to be a moderately broad, even, 
two-ridged, transverse band. 
The metanotum (Fig. 11) repeats the general appearance of the meso- 
notum and is of the same size, the wings being alike. The praescutum 
is not visible. The scutum is deeply divided into two halves, each 
half minute and much swollen. The scutellum as in mesonotum, but 
considerably larger. The post-scutellum is very distinct, forming a 
transversely-oblong piece no wider than the scutellum. 
Calopteryx (PI. XLVIII, figs. o-G) is substantially as in Agrion, as 
regards the notum. 
In JEsclma lieros th & pronotum is small and narrow, and nearly con- 
cealed from above by the head. It is about two-thirds as long as broad, 
divided into a short transverse ridge and a posterior, longer portion 
subtriangular behind, by a deep constriction or impressed line. 
Mesonotum. (PI. XLVIII, fig. 3.) The praescutum obsolete, not visi- 
