8 Gr. C. Crampton and W. H. Hasey, 



The tendency of the meron to migrate upward toward the lower 

 region of the epimeron, is clearlj' shown in the Trichoptera (Fig. 5); 

 and in the thorax of Maniispa (Fig. 13) the meron, me, is very 

 closely connected with the lower portion of the epimeron, hem. In 

 the lower Diptera, such as the Tipulidae, the meron, me, (Fig. 14) 

 occupies the normal position with reference to the anterior region 

 of the coxa, vc, and the lower portion of the epimeron, hem, yet 

 practically everyone who has figured these insects interprets the 

 region me, as the "posterior portion of the sternum". To anyone 

 studying the series of insects figured in the accompanying plates, 

 however, it will be quite obvious that the region me of Fig. 14, 

 occupies the position characteristic of the meron of other insects. 

 When the coxal region is spread out as in Fig. 15, it can be readily 

 seen that the sclerite me of the Tipulidae, is not connected with 

 the sternum at all, but is closely united with the remainder of the 

 coxa VC, from which it is demarked by the suture /, which is a 

 ventral prolongation of the pleural suture g, as in all other insects. 

 Furthermore, the same muscles which are attached to the meron in 

 other insects, are attached to the region me in the Diptera (Figs. 14 

 and 15); so that the only logical conclusion to be drawn from a 

 thorough study of the region in question, is that it is homologous 

 with the meron of other insects. This fact seems so very evident, 

 that it is difficult to understand how that anyone could have arrived 

 at any other conclusion. 



The fact that the meron me has completely fused with the 

 epimeron em, in the mesothorax of Panorpa (Fig. 4) indicates a 

 tendency on the part of the meron to unite with the lower portion 

 of the epimeron in the higher insects; and the migration of the 

 meron upward toward the pleural region in certain insects 

 (Figs. 5, 13, etc.) has already been pointed out. It is therefore not 

 surprising to find that in the higher Diptera, the meron has migrated 

 up into the pleural region, and has united with the lower portion of 

 the epimeron, to form the region designated as «?pZ, in Fig. 11. The 

 region mpl of Fig. 11 corresponds roughly to the fusion product of 

 sclerites me and hem in Figs. 13 and 14. On this account, the 

 region mpl of the higher Diptera (Fig. 11) has been designated as 

 the meropleurite (Ceampton, 1914) to indicate that it is the fusion 

 product of the meron and lower portion of the pleural region. 



Those who interpret the region mpl of Fig. 11, or the sclerite 

 me of Fig. 14, as the "posterior portion of the sternum", regard the 



