S PROCEEDINGS: BOSTON SOCIETY NATURAL HISTORY. 
corners is the mesonotum (PI. 4, fig. 25). The two swellings are the 
humeral callosities (PI. 3, fig. 18; PI. 4, fig. 25, hu.), the upper portions 
of the pronotal lobes (PI. 3, fig. 18, pul.). The transverse suture (PI. 3, 
figs. 18, 20; PI. 4, fig. 25, tsu.) crosses the mesonotum just forward 
of the wings, marking off an anterior region, the prescutum (PI. 3, 
figs. 18, 20; PI. 4, fig. 25, prsc). Behind this are the scutum (PI. 3, 
figs. IS, 20; PI. 4, fig. 25, sc.) and scutellum (PI. 3, figs. 18, 20; PI. 4, 
fig. 25, scL); the former a subquadrate area somewhat larger than 
the prescutum, the latter a much smaller plate of more or less hemi- 
spherical outline separated from the scutum by a deep transverse 
impression. 
On the side of the thorax, the pleural suture (PI. 3, fig. 18, plsu.), 
which separates the episternum and epimeron of the mesothorax, may 
be traced downward from the pleural wing process (PI. 3, fig. 18, pwp.) 
to a point just above the middle coxa. Internally the course of this 
suture is marked by a strongly chitinized ridge (pleural ridge, ento- 
pleuron, or apodeme). The large imperfectly divided plate which 
comprises the greater part of the side anterior to the pleural suture, 
represents the meso-episternum fused with part of the sternum and 
pro-epimeron. It consists of two plates, an upper sclerite, the anepi- 
sternum (PL 3, fig. 18, ns.), and a lower, the sternopleurite (PI. 3, 
fig. 18, sple.). Just below that part of the sternopleurite which pro- 
jects under the prostigma it bears the remnant of the suture which 
originally separated the pro-epimeron and the meso-episternum. 
Between the posterior border of the anepisternum and the pleural su- 
ture are two basilar plates (PI. 3, fig. 18, hp.) and the pleural wing 
process supporting the base of the wing. Anterior to the anepister- 
num and between it and the lateral parts of the prothorax lies the 
anterior spiracle or prostigma (PI. 3, fig. 18, asp.). Its margins are 
formed by projections of the plates that surround it. The opening 
of the spiracle is a vertical slit fringed on both sides with hairs that 
completely cover it. Those of the anterior margin are longer and 
overreach those behind. In front of the upper half of the spiracle 
and extending backward above it is the pronotal lobe, the upper 
swollen portion of which is the humeral callus. x\nterior to the base 
of the lobe another part of the pronotum can be seen, while beneath, 
completing the closure of the spiracular area lies the pro-episternum 
(PI. 3, fig. IS, pes.). The latter has a median, rounded, basal projec- 
tion that fits into a corresponding hollow in the top of the anterior 
coxa. 
