394 PROCEEDINGS: BOSTON SOCIETY NATURAL HISTORY. 
considered to be an imaginary line extending roughly from the 
lateral aspect of the base of the mesocoxa, across the point, to 
the lower margin of the pronotum. 
Immediately in front of the meso-episternum, and posterior to 
the pronotal lobe of the prothorax, occurs a comparatively small 
elongate triangular plate, — the basalar plate (Crampton, 1914), 
the first parapterum of Snodgrass (1910). 
The term mesopleuron is a collective one, and will be used to 
designate the entire lateral portion of the mesothorax; it includes, 
therefore, the meso-epimeron, meso-episternum, and the basalar 
plate. 
The pectus is the rather extensive region on the ventral surface 
of the mesothorax between the anterior and intermediate coxae; 
posteriorly it is continued as a narrow tail-like piece between the 
latter coxae. It is composed of the fusion of the continuations of 
the meso-episternum with the mesosternum. It is widely and 
roundly emarginate anteriorly, and is divided into similar halves 
by a median longitudinal suture. 
The tegulae are the small, strongly chitinized, scale-like plates 
which lie over the anterior portions of the bases of the anterior 
wings. 
Metathorax. — The metascutum is irregular both in outline 
and in surface. It is free in front on the dorsal surface, and 
extends over the invaginated meso-postscutellum nearly to the 
posterior visible portion of the mesothorax. Anteriorly it is 
seen as two narrow blunt ridges, one on each side, extending 
somewhat obliquely forward, and connected by a narrow, trans- 
verse, median piece immediately in front of the metascutellum. 
Each of these ridges bears on top a small, pale, scale-like cenchrus 
{pi. cenchri). Postero-laterally the metascutum, like the meso- 
scutum, drops down abruptly into the deep metathoracic sinus. 
The metascutellum is apparently much wider than long owing 
to its being doubled or rolled upon itself. In position it bears 
the same relation to the metascutum and meta-postscutellum, 
that the mesoscutellum bears to the mesoscutum and meso- 
postscutellum, being situated medially and bounded by the 
metascutum anteriorly, by the metathoracic sinuses laterally, 
and by the meta-postscutellum posteriorly. Again like the 
mesoscutellum, it is continued transversely on each side from its 
