NO. 16S7. 



THE THORAX OF lySECTf^—^XODaRAStS. 



523 



-ANP-^, 



V -^_^ Em 



becomes divided into the nioie or less definite regions nsnally called 

 the prcsc2itu/)i, scutum, and scutelluin, while the postnotuni remains 

 undivided and is the postscutelliim. The postnotuni does not occur 

 in the Orthoptera ; it does not occur in the nymphs of any insects, 

 even though well developed in the adults; it does not occur in the 

 pupa^ of Neuroptera and Coleoptera at least; and it is never present 

 in the prothorax. Therefore it is most probably not a i)rimitive 

 terfjid plnte, and the term pHeudonotum fits it very well. Verhoeif 

 (ItXK)) gave this name to the postnotal plate of the Euplexoptera 

 (Dermaptera), though he may not have intend(Ml its general rs> i i 

 the sense here applied. 



Text figures 1 and 2 

 diagrammatically rep- 

 resent the relation 

 of the notum (.V) 

 and the pseudonotum 

 {PN) to each other 

 and to the wing, the 

 last being carried en- 

 tirely by the notum. 

 Fig. 3, representing a 

 segment in side view, 

 shows the pseudo- 

 notum continuous lat- 

 erally wnth the epi- 

 merum {Epm). This 

 is the most frequent 

 condition, t h o u g h 

 often there is a line 

 between the two and 

 sometimes they are 

 only articulated or 

 m e r e 1 y contiguous. 

 This figure and figure 2, giving a ventral view of the tergum, both 

 show the postphragma {Pph) depending from the posterior edge 

 of the pseudonotum, though it is often restricted to the middle of the 

 latter. 



The pseudonotum alwa3^s carries the postphragma. Verhoetf re- 

 gards it as a development of the postphragma, but it is probabl}' 

 a better statement of the facts to say that the phragma is a develop- 

 ment of the pseudonotum, for in the lower insects the latter is a 

 large flat plate, while the phragma may be simply a thin fold pro- 

 jecting downward from its posterior edge. In the mesothorax of 

 Lepidoptera, Hymenoptera, and Diptera this condition, however, 

 is reversed, the phragma being developed to a great size, although the 

 pseudonotum itself is not reduced. The postphragma is really a 



Ppb. 



FlC. 1. — ItlACUAMMATli- TEUCIM OF AXY COMPLETE WIXG- 

 BEARlXCi SKli.MlOXT, AND TllK I'.ASIO OF THE WING, 

 DORSAL VIEW ; lA, FIUST ANAL VEIN ; AVP, ANTERIOR 

 NOTAL WING PROCESS ; unr, LINE OF ANTERIOR VKX- 

 TIIAL NOTAL RIDGE {ANR OF FIG. 2); AwC, AXILLARY 

 cord; AxM, AXILLARY MEMBRANE; C, COSTA ; Cu, 



CUBITUS ; Em, lateral emargination ok notum ; 

 If, media; Mb, membrane between notum and 

 pseudonotum ; V, notum ; I'N, pseudonotu.m or post- 

 notum ; rXP, posterior notal wing process ; par, 

 line of posterior ventral notal ridge (Pyii OF 

 FIG. 2); Pph„ postphragma; R, radius; 8c, sub- 

 cosTA ; Tg, tegula ; r, line of median or V-shaped 



VENTRAL notal RIDGE (T OF FIG. 2). 



