— 52 — 



makes it entire ; if these two sclerites do not meet, as is 

 often the case among beetles, and the cavity is bounded 

 caudad simply by membrane, the cavity is said to be open. 

 If there is no caudal tongue projecting between the cavities, 

 they are said to be confluent ; when separated, as in the 

 specimen in hand, by this tongue, they are technically 

 separate. 



MESOTHORAX. 



Dorsal aspect. — When the wing-covers are folded the 

 only part of the mesouotum visible is the small, median, tri- 

 angular or shield-shaped portion of the scutellum. By 

 spreading apart or breaking away the wing-covers, the lateral 

 membraneous portions of the scutellum may be seen, as well 

 as the scutum ; the median part of the scutum is strongly 

 chitinized and the lateral parts, weakly chitinized. The 

 postscutellum also may be distinguished as a narrow, weakly - 

 chitinized, curving bar, running laterad on each side just in 

 front of the caudal apex of the scutellum. The praescu turn 

 is represented merely by a thin, transversal strip of mem- 

 brane. 



Ventral aspect. — As with the prothorax the ventral 

 aspect of this segment is composed of the sternum and the 

 pleural sclerites. 



Mesosternum. — The mesostemum is plainly set off b} r 

 sutures. Its caudal margin has a broad, median tongue, 

 which projects caudad between the coxal cavities, and is 

 angularly emarginated at its tip. L,aterad of this tongue are 

 two, rounding emarginations, for the reception of the coxae. 

 Bounding each coxal cavity laterad is a caudad-projecting 

 portion of the sternum. Cephalad the sternal sclerite tapers 

 somewhat, and the cephalic margin is narrowly truncate. 

 A narrow, collar-like cephalic margin which fits into the pro- 

 thorax, is separated from the rest of the sternum by a slight 

 carina or elevated line. 



