Nov., 1902 .] 
Passalus Cornulus. 
3°7 
rated by a sharply defined groove except at the posterior end. At 
this point it is fused with both the sternum and epimeron to form 
the lateral articulation for the metathoracic coxa. Anteriorly it 
gives off a dorsal process which forms part of the wing articula- 
tion and lies between similar processes on the scutum (5) and 
epimeron (3). On its dorsal surface it is in contact throughout 
its whole length with the epimeron. The suture separating the 
episternum from the epimeron is best seen on the dorsal process 
and on the anterior half of the dorsal surface. Its boundaries are 
ventrally the sternum, anteriorly the scutum, and dorsally the 
epimeron. 
The epimeron (3) is a somewhat ill-defined sclerite lying 
dorsally to the episternum with which it is in contract throughout 
its whole ventral border. It consists of a strong narrow, chitin- 
ized bar with an anterior dorsal process which with similar pro- 
cesses from the episternum and the scutum form the ventral articu- 
lation for the wing. This sclerite can be easily separated from the 
episternum on its anterior half. Its posterior half is fused with the 
episternum. The dorsal boundaries of this sclerite are less definite. 
The anterior half bears a large, slightly chitinized triangular area, 
the posterior end of which articulates with a lateral process from 
the postscutellum. Excepting this triangular area the dorsal 
boundaries of this sclerite seem to be membraneous. 
The first abdominal spiracle (25) lies above the posterior 
border of the epimeron in a membranous area and is over two mil- 
limeters in length. It is placed in a slightly more oblique posi- 
tion than the mesothoracic spiracle, and its hinder border lies di- 
rectly under the second abdominal spiracle. 
The metanotum (4-7) forms the dorsal wall of the meta- 
thorax extending from between the wings as far back as the first 
segment of the abdomen. It is variously marked with chitinized 
bars and membranous areas so that the boundaries of its separate 
sclerites are hard to locate. In attempting to determine these dry 
specimens should be used to determine the sutures and moist ones 
to determine the articulations. The prescutum (4) lies just back 
of the meso-scutellum, its median rod-like portion being concealed 
by the meso-scutellum. It is dumb-bell-shaped and its enlarged 
ends form part of the anterior squarish end of the metanotum. It 
extends on either side of the median line to points even with the 
lateral edges of the meso-scutellum. It is bounded posteriorly by 
the chitinized bar extending across the body between the articula- 
tion of the wings. The scutum (5) is a small sclerite lying directly 
beneath and in front of the articulation of the wings. Its ventral 
border rests on the meso-epimeron (3). Its posterior border rests 
on the anterior bar of the met-cpisternum (2) : dorsally it assists 
in forming an articulation for the w r ing, and on the median border 
