6 THE THORAX. 



With Nematus, again, there is no great difference in 

 size. Pinicola appears to have three-jointed palpi. 



Save with Tar pa the labium and maxilla are incon- 

 spicuous. In Tarpa they are long and projecting. 



The Thorax. 



The thorax forms a compact mass, and is usually 

 slightly broader than the head, and of the same width 

 as the abdomen. The prothorax (PI. X, fig. 1, 17) is 

 small, the only portion visible from above being that 

 part often denominated the " collar," a part which , 

 from its being separated from the lower or leg-bearing 

 portion, has by some been regarded as a distinct 

 piece. The " collar " (pronotum) is firmly united to the 

 mesothorax, from which it is not readily detached. 

 Looked at from the side it is somewhat triangular as it 

 issues from the base of the mesothorax, where the wings 

 are inserted, towards the head, and from that curves 

 down towards the legs ; the same being the case on the 

 inner side, so that it becomes quite narrow at its lower 

 part (PI. XY, fig. 11 a). The episternum (1. c. I) is 

 shorter and stouter than the " collar," and slightly 

 broader at the bottom than at the top. It is much freer 

 in its attachment than the pronotum, and comes away 

 easily, carrying the legs and head with it when pulled 

 from its attachment. The prosternum is a small piece 

 situated between the episternum and the two coxae 

 (PI. XY, fig. 7, prosternum of Dolerus). 



The mesothorax is very large compared with the two 

 other portions. The scutum and scutellum form one 

 piece, the latter being generally flat and but slightly 

 raised above the scutum, but is usually sharply cut off 

 from the metanotum by the ridge which separates the 

 latter from the mesothorax. The mesonotum is divided 

 by depressions into three parts, a triangular one in 

 front and one on either side, the first being called the 

 "front" or "middle" (PI. X, fig. 1, 18), and the 

 others the " lateral " lobes of the mesonotum (PI. X, 



