AMERICAN DIPTERA. 373 



dorsum, where they are arranged in four rows; one on either 

 side of the geminate stripe, and one on each side of the lateral 

 margins. The bristles of the scutellar margin, and the red 

 bases and apices of the femora, and the bases of the tibiae, 

 are also striking. 



Specimens in the National Museum, and in the collection 

 of Prof. C. W. Johnson, do not have the bases of any of the 

 femora red, thus agreeing with six females and four males 

 from Kern County, mentioned by Dr. Williston. One of the 

 specimens from northern California has the base of the femora 

 and the tip of the tibia red. In the two females before me, 

 there are no black bristles in the mystax, and the bristles be- 

 fore the halteres are white, and not black. Dr. Williston 

 states that the number of scutellar bristles ranges from six to 

 ten, so their number is of no specific value; and that the 

 bristles of the tibias of the male are white, while those of the 

 female are mostly whitish, but in part black. 



TARACTICUS. 



Taracticus Loew, Cent., X, 24; note, 1872. 



Dioctrodes Coquillett, Proc. Ent. Soc. Wash., VI, 181, 1904. 



Form of head as a whole similar to Dioctria, especially as 

 regards the mystax and antennae, but the front tibiae with a 

 terminal claw-like spur. Head nearly twice as broad as high : 

 face gently convex, the oral margins not at all as prominent ; 

 mystax composed of a few weak bristles, for the most part 

 confined to the oral margin. Antennae (PL III, fig. 6) slender, 

 elongate, segment 3 sometimes three times the length of seg- 

 ments 1 and 2 taken together, microscopically pubescent, be- 

 yond its center on the upper side with an emargination at the 

 proximal end of which there is a short forward directed spine. 

 Facial and frontal orbits nearly parallel, the latter slightly 

 emarginate; ocellar tubercle of good size. Body of male 

 slender, of female more robust; in each the abdomen is very 

 convex, punctate and nearly bare. Genitalia hardly notice- 

 able. Scutellum with two marginal bristles. Legs slender; 

 hind tibiae incrassate, hind tarsi very robust; front tibiae with 

 a terminal, though weak, claw-like spur. Marginal, submar- 

 ginal, posterior, and anal cells open. 



TRANS. AM. ENT. SOC, XXXV. SEPTEMBER, 1909 



