128 Proceedings of the Royal Physical Society. 
Viewed ventrally, the prosternum is distinct, being defined by two ridges 
running from the anterior border to the coxe. The coxe are almost 
contiguous. 
Mesothorax.—Viewed dorsally, this region is almost completely hidden by 
the prothorax anteriorly and by the elytra posteriorly, only the circular 
scutellum being visible. If the prothorax and elytra are removed the 
Fic. 8.—H. ater 3, Pk. (dorsal aspect). (Right elytron and part of pronotum removed.) 
a. Head. jf. Prescutum of metathorax. 
h, Prothorax (pronotum), g. Mesoscutum of metathorax. 
c. Mesothorax (mesonotum). h., Postscutum of metathorax. 
d. Scutellum. : sp. Spiracles. 
e. Elytron. 1, 2, 3, etc. Abdominal tergites. 
following regions can be recognised—the prescutwm, the scutwm, and the 
scutellum. The prescutum and the circular scutellum are strongly chitinous. 
The scutum and the lateral extension of the scutellum are soft and flexible. 
The prescutwm is peculiar in shape. Its anterior border is roughly V-shaped. 
Its lateral borders diverge about the middle to form a lobe and then taper 
posteriorly to meet the scutellum. The scutwim is rudimentary and is divided 
from the lateral extensions of the scutellum by a mere line of folding. The 
scutellum is knob-like and extends laterally as a thin band of flexible chitin. 
Viewed from the side, the mesothorax shows the episternum lying 
anteriorly, and the epimeron adjoining it posteriorly. Both are irregularly 
triangular in shape. 
