306 REPORT UNITED STATES ENTOMOLOGICAL COMMISSION. 
are inserted at the posterior end on the side of each segment (basno- 
mere), as the coxae are widely separated by the very large and broad 
sternites. 
Propleurites. (PI. XXIV, fig. 1.) These are well developed. The 
episternum is horizontal, flat, subtriangular, narrow, reduced to a 
point before reaching the coxa. A wedge-shaped, triangular sclerite is 
wedged in between it and the sternite (this may be regarded as the sub- 
episternum, though possibly the trochantine, as the coxa is apparently 
entire, and there is otherwise no trochantine to be found). 
The epimerum forms the upper part of the pleurum, and is scale-like, 
oblong-oval; in front it is narrow, and ends at the anterior margin of 
the notum. The posterior or upper end of the epimerum is free, rounded, 
scale-like, as it covers the prothoracic stigma. 
The coxa is cylindrical, shorter than broad. I can perceive no suture 
in it, and think the trochantine is obsolete. 
Mesopleurites. (Fig. 2.) These sclerites repeat the form of the pro- 
pleurites. The segment (bsenomere) is not so long, and the sclerites 
are a little more horizontal. The epimerum is more regularly oblong- 
oval, with a deep crease or fold below the middle, which extends ob- 
liquely from near the coxa to the front edge of the epimerum. 
The episternum is iu this segment, as in the preceding one, divided 
into two pieces ; the sur-episternum is very small and situated in the 
same plane as and on the side of the anterior end of the sternum. The 
triangular sub-episternum is more oblique than in the propleurum. The 
coxa is smaller than in the prothorax. 
Metapleurites. (Fig. 3.) The structure of this region is very remark- 
able, as compared with that of other Phyloptera. The episternum is 
simple, not subdivided as in the pro- and mesopleurum, but represented 
by an acutely triangular sclerite, the base of which lies next to the 
coxa, the acute apex reaching only two-thirds the way to the front of 
the sternum. This reduction in the size of the episternal elements is due 
to the increase in size of the sternum below and the epimerum above. 
The epimerum is enormously developed, extending from the insertion 
of the hind wings (which is very near that of the anterior pair) back 
nearly to the middle of the second abdominal segment; it thus forms 
the side of about half the entire thorax ; in situation it is horizontal, 
its sides vertical, but in front next to the mesocoxce and sternum it 
rounds down and under, becoming ventral. (This is a most novel mod- 
ification of the met-episternum, and as unique as the modification of the 
mes-episternum in the Odonata.) 
Coxae longer than in the mesotliorax, and soldered to the steruum. 
Sternum. 
The sternal elements are in Forficulidae remarkably large and broad, 
the species being essentially runners. 
The prosternum is subdivided into a single, large intercoxal plate, 
