MUSCULATURE OF DIPTERA — SMART 333 



Dr. Snodgrass himself contributed to our knowledge of the internal 

 anatomy of Diptera in the course of his monograph on the honey bee 

 (Snodgrass, 1925) and elsewhere. But it was not till Partmann 

 (1948) published a paper — with an omnibus title that somewhat 

 obscured the nature of its contents- — containing some notes on the 

 anatomy of the mesothoracic, indirect flight muscles of Diptera, that 

 it became apparent that there was something peculiar in the histology 

 and anatomy of these muscles as well as in their possession of the 

 highly specialized physiological properties already recognized 

 (Wiggles worth, 1939; Chadwick in Roeder, 1953; Pringle, 1957; 

 and others). Unfortunately Partmann himself did not fully realize 

 what he had discovered, and it remained for the late Prof. O. W. 

 Tiegs to show that the "muscles" comprised in the indirect flight 

 muscles of the mesothorax of Diptera are in the nature of giant fibers 

 and not compact bundles of small fibers (Tiegs, 1955)- 



Tiegs (op. cit.) examined a more extensive series of Diptera than 

 did Maki, and he showed that the anomalies in the musculature - to 

 which Maki had drawn attention were not a peculiarity of the tipu- 

 lids. This author (1957, 1958) has also added to the information 

 available about these two anomalies. 



The general topic of insect flight has recently been reviewed by 

 Pringle (i957)- 



3. THE THORACIC EXOSKELETON OF ANISOPUS 

 Figure i is a lateral view of the thorax of Anisopus fenestralis 

 Scopoli. The figure is on the same scale as figures 2 and 3, which 

 show the extent of the mesothoracic postnotum and its phragma which 

 is partly covered by the metathorax and the first abdominal segment 

 in the lateral external view. 



The parts of the exoskeleton of Anisopus can be named without 

 much difficulty. The prothorax is complete dorsally and quite dis- 

 tinct from the mesothorax. It has a distinct pleural sulcus ; the coxa 

 of the fore leg is large and mobile; well-developed cervical sclerites 

 support the head. 



In the mesothorax the dorsum is divided into a gently arched scu- 

 tum with well-developed posterior callosities and scutellum ; articu- 

 lated to the scutellum is the large postnotum, on either side of which 

 are demarcated the so-called "laterotergites." 



2 Maki (1938) had found that his tipulid (i) had a well-developed coxo- 

 subalar muscle, which was not present in the other four Diptera he examined, 

 and (2) lacked the tergal depressor of the trochanter muscle possessed by all 

 the other four Diptera. 



