Xo. C4] DIPTERA OF COXXECTICUT : MORPHOLOGY 41 



(1929. p. 434) — which differ from his earlier views on the subject). 

 The hibrum, which usually forms the top and sides of the food chan- 

 nel, is quite short and extends forward only as far as the middle of 

 the bulbous basal portion of the proboscis, so that the food channel, 

 from this point onward, is formed by the upturned walls of the labial 

 gutter, which is continued into the narrower, anterior portion of the 

 proboscis formed by the labella. A cross section through the middle 

 of the proboscis (Fig. 4, C) would therefore show the food channel, /c, 

 formed by the walls of the labial gutter. It, with the hypopharynx, Ap, 

 (pierced by the salivary canal), which is also enclosed by the walls of 

 the labial gutter, situated above the food canal, /c, instead of form- 

 ing the floor of the food canal, as the hjq^opharynx does when the 

 roof of the food canal is formed by the labrum in the muscoid flies, 

 etc. (Fig. 4, F). The elongated labella bear chitinized teeth, which ap- 

 parently aid in the piercing operations of the proboscis. 



In the Streblidae the labial gutter is well developed, and extends 

 through the middle portion of the haustellum. into the labella. The 

 j walls of the labial gutter project mesally under the hinder portion 

 of the hypopharynx, and interlock in such a way as to divide the 

 labial gutter into a dorsal canal, which serves as a salivary canal, and 

 a ventral canal, which serves as a food channel. The labella are 

 armed with well developed teeth, which serve to penetrate the flesh 

 when the proboscis pierces a wound: and Jobling (1929, p. 437) states 

 that in the peculiar streblid Ascodipteron "the teeth of the serrated 

 ridges of the labella in the female are enormously developed and 

 serve to pierce the skin as well as to drag the insect into the wound, 

 where it becomes encvsted after shedding the legs and wings." 



Morphology of the Thorax and Its Appendages 



The best description of the thoracic and basal abdominal sclerites 

 of the Diptera is that of Young (1921), who has described these parts 

 in practically all of the dipterous families. Young's studies are sup- 

 plemented by the papers of Crampton (1925-1926) on the thoracic 

 sclerites of the nematocerous Diptera. Figures of the thoracic struc- 

 tures of the Diptera in general are given in the discussions of the 

 "parts by Hendel (1928), Patton and Cragg (1913), Walton (1909), 

 Brauer (1882), Snodgrass (1909 and 1935), Martin (1916), Crampton 

 (1926), and others, while the thoracic sclerites of individual Diptera 

 are figured in the works of Kuenckel d'Herculais (1875), Hammond 

 (1881), Lowne (1890), Ritter (1911), Hewitt (1914), Parker (1914), 

 Prashad (1918), Bromley (1926), Balfour-Browne (1932), and Rees 

 and Ferris (1939). 



Grimshaw (1905), de Meijere (1901), West (1861), Crampton 

 (1923), Crampton and' Hasey (1915), Walton (1909), Hendel (1928),, 

 and Holway (1935) etc., have discussed the structure of the legs of 

 Diptera, while Comstock, in his "Introduction to Entomology,"' and 

 in his "Wings of Insects," has figured the venation of the wnigs in 

 most of the families of the Diptera : and figures of dipterous wmgs 

 are to be found in the works of Yerrall (1901-1909), Williston (1908), 



