NO. I 



INSECT THORAX — SNODGRASS 



77 



posterior basicoxal lobe of the larva. The continuity of the meron 

 and the epimeron during the pupal stage is, therefore, hut a secon- 

 dary and temporary union of these parts in the Neuroptera and Tri- 

 choptera, as claimed l)y Crampton and Hasey (191 5). but it fore- 



Tz ^Nj Tj PNj, J7 



Fig. 34. — Modifications by which the mesothoracic meron, normally a basal 

 lobe of the coxa, in the Diptera becomes a plate of the body wall. 



A, mesothorax, metathorax, and base of abdomen of Panorpa consuetudinis: 

 meron (Mcr) forming a large lobe on posterior face of each coxa. 



B, mesothoracic and metathoracic pleura and coxs of a tipulid fly (Holorusia 

 grandis) : meron of mesothorax (Mcr2) a large coxal plate projecting into 

 pleural wall. 



C, mesothoracic and metathoracic pleura and middle coxa of horse fly 

 {Tahaniis atratus) : mesothoracic meron {Mcr^) detached from coxa (Cf:), 

 and incorporated into body wall. 



D, median section of thorax of a syrphid fly (Eristalis fcnax) : the remotor 

 muscle of middle coxa (J) becomes a wing elevator, by transfer of the meron 

 (Mcr.:) from coxa to body wall. 



shadows a permanent displacement of the meron in the mesothorax 

 of Diptera. 



The meron region of the coxa bears the ventral attachment of the 

 subalar epipleural muscle (fig. 37 B, F), and of the remotor of the 

 coxa (/). A plate in the ventrolateral wall of the mesothorax of 

 Diptera, lying above and behind the base of the coxa, constituted a 



