342 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. I37 



The great modifications in the general condition of the sternal 

 region of the mesothorax and the disappearance of the trochantin 

 coupled with the lack of any clear subdivision in the tergosterno- 

 pleural muscle had led dipterists to use purely descriptive names to 

 designate the parts thereof. 



D. PLEURAL MUSCLES. 



The muscles comprised in this group (fig. 4) are all of the usual 

 tubular, tetanic type vi^ith the single exception of the coxosubalar 

 muscle (10) which (Smart, 1957) consists of two giant fibers similar 

 to those constituting the main indirect flight muscles dealt with above. 



These pleural muscles can be grouped as shown in table 2. In two 

 cases single muscles could be alternatively placed in one or the other 

 of two different groups. These are shown in both possible positions, 

 but in one position the index letter is in parentheses. Below, the 

 muscle is dealt with in the order indicated by the index letter not in 



Table 2. — Mesoplcural muscles of Anisopus (Group D in table i) 

 7. TERGOPLEURAL 



a. Tergobasalar. (See also as 8, c below) 



b. Tergopleurosulcal 



(c). ? 9, c, i, classifiable here 



BASALAR 



a. Anterior episternal basalar 



b. Inferior episternal basalar 

 (c). ? 7, a, classifiable here 



AXILLARY 



