ODONATA. 
331 
ble from above. Scutum subtrapezoidal, longer than broad; acute 
bebiud, with an appendicular area between the conical end aud the scu- 
tellum, cousistiug of two diverging tubercles, from which a narrow ridge 
falls away on each side, forming the origin of the 5th vein of the wings 
on each side. (Fig. 3, v. 5.) 
The scutellum is swollen, triangular, as broad as long, the apex 
directed backwards and wedged in between the separate halves of the 
post-scutellum, which is represented by two triangular bosses, the apices 
separated by the pointed end of the scutellum, the bases connected by a 
ridge concealed by the end of the scutellum. 
Metanotum. (Fig. 4.) There is a pair of patagia, one in front of the 
base of each hind wing. No praescutum. The scutum is much larger 
than the mesoscutum, a little longer than broad; each side raised into 
an oblong-oval boss, with a narrow, acute, triangular, depressed, flat 
area between, and bounded behind by a converging ridge, which is suc- 
ceeded by a peculiar diverging ridge (v. 5), like that in the mesonotum, 
which is the origin of the 5th vein of the second pair of wings. 
The scutellum is much larger than in the mesonotum, nearly square, 
smooth and flat ; the posterior one-half vertical, thin, and more or less 
elastic aud membranous, moving upon the abdomen. (This posterior 
portion may represent the post-scutellum, which is otherwise absent, but 
there are no signs of a suture.) Post-scutellum absent ('?) See Fig. 4, 
p. scl.", for what may prove to be the post-scutellum. 
Pleurum. 
In Agrion (Fig. 7) the pro-episteruum and epimerum of each side are 
minute, rudimentary, aud submembrauous, and in position are vertical, 
Mcsopleurum. The episternum in the Odouata differs remarkably 
from all other Pseudoueuroptera aud indeed from all other iusects, only 
the Acrydii approaching them in the enormously long aud large epi- 
sterna, which meet in front to form a large, dorsal, convex area, that usu- 
ally occupied in other insects by the scutum. The epimerum is a similar 
piece, and nearly as large as the lateral portion of the episternum ; it 
is in Agrion consolidated with the meta-episternum. In Calopteryx, 
however (Fig. 6), where the thorax is broader aud higher, the two scle- 
rites are separate. 
The coxae are small, conical; the trochantiue is small, triangular, and 
situated directly over the small couical coxa. 
Metapleurum. (Fig. 8.) The episternum repeats the form of that of 
the mesopleurum, but is consolidated with the meso-episternum. The 
episternum, seen laterally, is regularly oblong, and three times as long 
as broad. 
The trochantiue is a triangular piece, situated directly over the small 
subconical coxa. 
In Calopteryx (Fig. G) the meso-episternum and epimerum are much 
