76 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 80 



(fig. 33 G, d), and probalily in the majority of insects it is lack- 

 ing(H). 



The inflection of the outer wall of the basicoxite to form the 

 pleural articular surface of the coxa (fig. 33 A, b) divides the basi- 

 coxite externally, and the two lateral basicoxkl parts often beome 

 enlarged in the form of two lobes on the coxal base (fig. 33 C), one 

 before the pleural articulation, the other behind it. The posterior 

 lobe, which is usually larger than the other, is the meron (Mer), 

 though, as presently will be shown, quite dififerent parts of the coxa 

 have been confused under this term. The basicoxal lobes are well 

 developed on the middle and hind legs of a cicada (figs. 16 D, 33 F), 

 the meron of the hind leg of an adult cicada bearing a large hollow 

 spine-like process. 



The meron is often much enlarged through being extended distally 

 on the posterior part of the coxa (figs. 31 A, 33 H), but even if it 

 reaches almost to the end of the coxa (figs. 33 G, 34 A), it still pre- 

 serves the relation of a basal lobe to the rest of the coxa, for it never 

 takes part in the trochanteral articulations. The suture limiting the 

 meron is always an extension of the basicostal suture (be), and its 

 internal ridge separates the bases of the coxal muscles of the meron 

 from those of the trochanteral muscles attached within the body of the 

 coxa. By this test, the meron of a coxa lacking a true lateral suture 

 (fig, 33 H), and the posterior part of a coxa divided by this suture 

 (E, d') should be easily distinguished, but the mistake of identifying 

 one with the other has often been made. In the middle and hind legs 

 of Blattida; (fig. 31 A), the distal part of the basicostal suture (be) 

 defining the elongate meron is obsolete, giving the meron the appear- 

 ance of being a part of the coxa, but in Termitidse, with a similar 

 meron, the suture is complete, and the meron is a typical basicoxal 

 lobe. 



In adult Neuroptera, Mecoptera, Trichoptera, and Lepidoptera, 

 the meron of the middle and hind legs is particularly large, often 

 reaching to the distal end of the posterior face of the coxa (figs. 33 G, 

 34 A, Mer), though in the larval stages it is an inconspicuous lobe 

 on the coxal base, or is not distinguishable (Lepidoptera). The 

 growth of the meron takes place during the pupal stage, and its 

 apparent continuity at this time with the epimeron above it, in 

 Neuroptera and Trichoptera, led the writer, in a former paper 

 (1909), to the conclusion that the adult meron in these orders is 

 derived from the epimeron. A study of the musculature, however, 

 shows the identity of the large adult meron with the inconspicuous 



