144 



PHYSIOLOGY OF INSECTS. 



— L 



N 



impossible to determine the commencement or termination 

 of either of these segments. The space intervening be- 

 tween the prothorax, C — D, and the 

 podeon, K — L, is so intersected with 

 _ lines, and so complicated in its struc- 

 ture, that it seems almost impossible to 

 "^^ apply to it any nomenclature of parts 

 that shall correspond with that used 

 —F either for Coleoptera or Hymenoptera. 

 It fortunately happens that the nomen- 

 clature of these parts is not particularly 

 essential in descriptions of the locusts, 

 the form of the prothorax being taken 

 as a better guide to the discrimination 

 y of genera and species. To return to 

 V the 'propodeon^ we find that this and the 

 X following segments never bear organs 

 " ^ of locomotion of either kind. The pro- 

 Locttst podeon of the Phasma and Mantis is a 



distinct, perfect segment, but in the lo- 

 cust it appears to possess a dorsal or upper surface only ; 

 the under surface oi \\\q podeon, L, apparently uniting with 

 the under sm'face of the metathorax, H. The propodeon 

 appears more essentially connected with the preceding 

 than following segment, for if a locust which has long 

 been preserved in a cabinet, and has become dry and 

 brittle, be broken in two, the propodeon will rather remain 

 with the anterior than the posterior half, the fracture 

 usually taking place at the line between I and K. 



The sixth segment, podeon or p)eduncle, is usually much 

 smaller than either of the preceding, although not mate- 

 rially so in the insects which have been chosen as illus- 

 trations ; in the locust particularly it is a large and robust 

 segment, exceeding in size the propodeon as well as the 



