MUSCULATURE OF DIPTERA — SMART 



343 



parentheses; the index letter entry in parentheses shows where it 

 might be placed along with other muscles of related function. 



7. TERGOPLEURAL MUSCLES (fIG. 4). 



Snodgrass (1935) assigned four muscles to this so-named group; 

 they connect the dorsum directly with the pleural wall. There are only 

 three muscles with such a function in the mesothorax of Anisopus. 

 The first muscle of Snodgrass's group, his "iB," appears to be miss- 

 ing in Anisopus; it is described as running from the "prealar arm of 



Fig. 4— Anisopus fenestralis Scop., upper part of pleural wall of right half 

 to show muscles related to wing base. Muscles labeled with index numbers 

 and letters used in the text. X 84. 



the tergum to the episternum." The specializations of the meso- 

 thorax of Diptera have resulted in apparent migration of the origins 

 of the muscles comprised in this group. 



a. Tergobasalar muscle. 



Other names are: Tergopleural muscle, "2B" (Snodgrass), "mus- 

 culus gracilis" (Ritter), first pair ordinary tergopleural muscles 

 (Maki), posterior tergal muscle of the basalare (Bonhag), and, pos- 

 sibly, muscle "50" of prealar apophysis (Miller in Demerec). 



Runs from the anterior notal wing process to the basalar plate. 



