344 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 1 37 



Specialization of the mesothorax has brought the origin of this muscle 

 into a position posterior to the origin of D, 7, b. 



If correctly homologized with Ritter's "musculus gracilis" it is 

 noteworthy that the proportionate size is much larger in Anisopus 

 than in Calliphora. It could, of course, be grouped with the other 

 muscles inserting on the basalar plate as 8 (c). 



h. Tergoplenrosulcal muscle. 



Other names are: Tergopleural muscle "3B" (Snodgrass), "mus- 

 culus anonymus" (Ritter), third pair ordinary tergopleural muscles 

 (Maki), tergal muscle of the pleural wing process (Bonhag), and 

 possibly basalar muscle ("52") (Miller in Demerec). 



Runs from the lateral margin of the scutum to the pleural sulcus 

 on which it inserts just anterior to and below the dorsal wing process 

 of the sulcus. 



(c). 



As pointed out below, muscle 9, c, i, could be grouped here. 



Snodgrass (1935) has a tergopleural muscle, designated 4B, which 

 should run from the posterior notal wing process to the pleural sulcus. 

 No muscle corresponding to this has been described as present in 

 Diptera; I believe that one of the muscles of the 4th axillary sclerite 

 is in fact this tergopleural muscle, 4B of Snodgrass. It is dealt with 

 further below (see 9, c, i: pleurosulcal muscle of the 4th wing 

 sclerite). 



8. BASALAR MUSCLES (fIG. 4). 



Three muscles attach to the conspicuous basalar plate. One, the 

 tergobasalar muscle (7, a) has been considered above as a tergopleural 

 muscle. The other two correspond to two of Snodgrass's three epi- 

 pleural muscles of the basalar plate. 



The basalar plate and its system of muscles has, in Anisopus, ro- 

 tated through a full 90 degrees clockwise as compared with Snod- 

 grass's diagrammatic representation of the musculature of the ptero- 

 thoracic segment (Snodgrass, 1935, fig. 103). 



0. Anterior epistcrnal basalar muscle. 



Other names are: Epipleural basalar muscle "lE" (Snodgrass), 

 may be "adductor alae secundus" (Ritter), anterior tergal muscle of 

 the basalare (Bonhag), muscle of prealar apophysis ("49") (Miller 

 in Demerec). 



