EXTERNAL ANATOMY OF INSECTS. 551 



the body : now, if it really represented the prothorax, 

 the under side of the segment, as in those Coleoptera in 

 which no suture separates the upper from the lower part 

 of the manitrunk 3 , should represent the antepectus, and 

 have the arms inserted in it; but in the case before 

 us there is a distinct antepectus bearing the arms received 

 by the socket formed by this annulus. But the most 

 powerful argument is the fact that some insects have 

 both the prothcn^ax and collar, a circumstance that com- 

 pletely does away every idea of their identity. If you 

 examine the common hornet [Vespa Crabro), or any 

 saw-fly {Tenthredo L.), you will find, as was before inti- 

 mated, that the real covering of the cavity of the mani- 

 trunk is a ligamentous membrane, which properly re- 

 presents the prothorax. In another genus of the same 

 order (Xiphydria Latr.), the sides of the antepectus turn 

 upwards and nearly form a horny covering distinct from 

 the collar b , the ligamentous part being reduced to a 

 very narrow line, and in Fcenus the dorsal fissure is quite 

 filled up, so that in this the manitrunk is perfectly di- 

 stinct, and exhibits both prothorax and antepectus of the 

 usual substance. In Nomada likewise, N. Goodeniana K. 

 was the species I examined, there is a short minute pro- 

 thorax besides the collar. Next let us turn our attention 

 to the Diplera; if you examine the common crane-fly 

 (Tipula oleracea), you will find, first, a regular short 

 prothorax, to which the antepectus, with the arms, is at- 

 tached ; and behind this also is a short collar embracing 

 the alitrunk anteriorly. The next insects that I shall 

 mention, as exhibiting both prothorax and collar, are the 



a See above, p. 536. b Plate IX. Fig. 14. 



