AMERICAN DIPTERA. 319 



of apical segment faintly gray pollinose ; first segment with lateral 

 comb of four or more black bristles. Ovipositor yellow, straight, twice 

 as long as its conical base and extending to apex of second segment 

 (Fig. 103). Legs black, except yellow knees, extreme bases of tibiae, 

 and basal joints of tarsi ; femora and tibiae more or less gray or sil- 

 very ; anterior and middle femora and hind trochanters each with two 

 strong bristles beneath near bases (Fig. 128). Wings hyaline (Fig. 

 187). Length and wings 3.5 mm. 



Type.— Troy, Idaho, V, 31, '08 (Cresso?i, A. N. S., No. 

 5027). 



This robust species may be recognized by the strong bristles 

 on the femora and hind trochanters beneath. 



50. P. unguiculatus n. sp. 



6". Similar to those placed under similis Hough, but more obscured 

 with brown. Abdomen ovate, broadest at third and fourth segments, 

 minutely granular, giving a subshining appearance, or, slightly metal- 

 lic lustre, with faint hoary tinge, especially the latter in a lateral spot 

 on fourth and fifth ; fifth longer than fourth, much narrowed apically, 

 and broadly indented dorsally, with minute black bristle-like hairs 

 laterally ; lateral comb of first distinct and yellow. Hypopygium as 

 long as fifth, assymetrical, cleft, much developed below, with inter- 

 mediate lobe just visible at sides (Fig. 107). Legs somewhat stouter, 

 darker; post-trochanters with a curved tooth near base below (Fig. 

 132) ; femoral spines weak. Wings hyaline (Fig. 176). Length and 

 wings 3.2 mm. 



One specimen. Falls Church, Va, May {coll. Banks). 



In the form and appearance of the abdomen this species 

 suggests subnitens, but the presence of the trochanteral tooth 

 at once separates it. 



51. P. appendipes n. sp. 



c?. Bare, subshining. Front and face silvery, former with a slight 

 yellow tinge. Antennae black or brownish, with third joint abruptly 

 acuminate, spiniform apically (Fig. 36). Occiput shining, tinged 

 with brown. Mesonotum and scutellum faintly brownish, the former 

 with minute but distinct dorso-central hairs. Metanotum with lateral 

 cinereous spots. Halteres and humeri yellow. Abdomen shining, 

 greenish-black, destitute of any pollen ; first segment with lateral comb 

 of long black hairs ; fifth narrowed apically, longer than fourth, but 

 as long ventrally as dorsally. Hypopygium equalling, or, shorter 

 than fifth, faintly pollinose, rather assymetrical, cleft, with interme- 

 diate lobe visible at side (Fig. 117). Coxae, femora except apices, 

 tibiae except the broad bases and extreme apices, black, otherwise 

 legs yellow ; femoral spines minute ; post-trochanters each with a 



TRANS. AM. ENT. SOC, XXXVI. JANUARY, 1911 



