THE METATHORAX. 7 



fig. 1, 19, :20). The middle lobe never reaches to 

 the scutellum, from which it is sometimes separated 

 by a deep depression. Close to the prothorax, and 

 where the wings are inserted, are two overlapping 

 horny points, often differently coloured from the sur- 

 rounding parts, called tegulce. 



The epistcrnuiii is a small three-angled piece situated 

 below the front of the wings. The mesosternum and 

 i era are well developed, and their usual form may 

 be seen by a reference to the figures (PL XV, fig. 11, 

 i/, //). The mesojphragma is made visible by remov- 

 ing the metanotum which lies over it. At its base it 

 stretches from one side of the thorax to the other, but 

 it narrows towards its apex, which curves down into 

 a sort of hook form, the apical part being split in two 

 (PI. XV, fig. 6, j from above, d from the side). 



The metathorax forms a narrow ring, and is never 

 larger than the basal segment of the abdomen. It is 

 separated from the mesothorax above by a deep 

 depression. On its front edge, and close to the scu- 

 tellum, are two white bead-like horny points, called 

 ccnchri (PI. X, fig. 1, 22), which are usually un- 

 protected, but with Li/da are covered with overlapping 

 hoods. Immediately behind this ring (which has a 

 distinct metasternum) there is, separated from it by a 

 groove, another arc which has no ventral continuation 

 (PI. XV, figs. 6, 12 a, 13 c) and bears a stigma (fig. 

 126). The precise signification of this segment has 

 been much discussed, some considering it to form part 

 of the abdomen, while others look upon it as belonging 

 to the metathorax. There can be little doubt that it 

 is a distinct segment, and if we regard the thorax as 

 being made up of three segments, then it would have 

 to be regarded as part of the abdomen ; but, on the 

 other hand, it seems clear that functionally it forms 

 part of the thorax, it having the muscular system, &c., 

 identical with the three preceding segments, besides 

 being much more intimately bound with the thorax 

 than with the abdomen. In other words, the thorax 



