PROC. ENT. SOC. WASH., VOL. 23, NO. 6, JUNE, 1921 133 



straight with acute distal extremities; the ventral sclerite of the salivary duct, 

 while not detached from the intermediate region, is very prominent; an articula- 

 tion now exists between the intermediate and basal regions; the dorso-anterior 

 angle of the dorsal wing of the basal plate is strongly produced anteriorly, while 

 the posterior portion of this wing presents a deep narrow cleft; the hypopharyn- 

 geal plates (Fig. 14) are irregularly quadrangular in form and paired; each pre- 

 sents an oval or rounded sensorial unchitinized area; the inner surface of the 

 labium bears a few rows of stout uncolored spines; the epipharyngeal plate 

 (Fig. 15) is emarginate posteriorly and produced anteriorly into a short rounded 

 tooth; it bears several sensorial areas as indicated in the figure. 



The puparium measures about 6.5 mm. x 3.0 mm.; it varies in color from lighr 

 to dark reddish brown; the surface is smooth without apparent rugosities or 

 excrescences and moderately polished; the puparial wall is sufficiently trans- 

 parent so that the cast third stage mouth hooks can usually be seen through the 

 cap; the anterior extremity is rounded or hemispherical; the anterior stigmata 

 are inconspicuous, not protuberant or elevated; the line of cleavage separating 

 the two halves of the puparial cap passes posteriorly on the ventral side of the 

 anterior stigmata and terminates just behind theanteriorspine bandof segment 

 IV; the circular line of cleavage runs perpendicularly to this point around the 

 puparium; the prothoracic cornicles traverse the puparial wall just in front of 

 the posterior margin of segment IV, slightly postero-dorsad to the posterior end 

 of the longitudinal line of cleavage of the cap; the posterior end of the puparium 

 is rounded conical or sub-conical; the posterior stigmata are situated slightly dor- 

 sad of the posterior apex; they are inconspicuous and scarcely elevated above 

 the surface of the puparium. 



The respiratory apparatus of the pupa has the form shown in the figure 16; 

 the internal spiracle is oval and presents 7 or 8 double rows of respiratory papillae; 

 the terminal portion of the prothoracic cornicle is rather slender and only mod- 

 erately chitinized, with a rather small number of spiracular openings (V\g. 17). 



THE ADULT. 



According to the system of classification based on adult 

 characters, this species belongs in the genus Zenillia R.-D. Dr. 

 J. Villeneuve has very kindly supplied me with the diagnostic 

 characters of this genus. 



The genus Zenillia, writes Dr. Villeneuve, has replaced the genera Myxexo- 

 rista B. B., Tritochaeta B. B.; the vibrissae become weaker as they approach the 

 upper part ot the facial plate and, especially in the female, cease to exist toward 

 the upper half or third of the facial plate; eyes hairy; no orbital bristles in the 

 male; front moderately broad; anterior claws of the male more or less elongate; 

 posterior tibiae with regular or irregular ciliation; third longitudinal vein bear- 

 ing bristles at its origin only; bend of the fourth vein without an appendage; 

 second segment of the arista not perceptibly elongate; apical bristles present 

 on the scutellum. 



The synonymy of the genus Zenillia, according to the Cata- 

 logue of Palaearctic Diptera, of Bezzi and Stein, is as follows: 



