296 E. T. CRESSON, JR. 



is present in both wings. The other, from the Black Moun- 

 tains (Fig. 136) has in both wings a well developed append- 

 age from the post-cross-vein into the discal cell. These 

 examples seem to point to the possibility that the absence 

 or presnce of the appendages should not be depended upon 

 as specific characters. 



Group II. 



Stigma colored ; abdomen more or less shining ; third section of 



fourth vein generally about tzvice as long as fourth. 



17. P. elegantulus Williston. 



<?. Front and face silvery; antenna? black; third joint silvery 

 pubescent, obtusely pointed. Mesonotum deep brown, moderately 

 shining, distinctly pilose ; pleurae and metanotum gray. Abdomen 

 deep black, shining, whitish pilose ; first segment, and lateral angles 

 of following, opake-gray. Hypopygium large, black, moderately shin- 

 ing, thinly pollinose, reddish below. Legs yellow ; femora stout, with 

 distinct spines, more or less broadly blackened medianly , apical joint 

 of tarsi black. Wings nearly hyaline; stigma yellow ; ultimate sec- 

 tion of fourth vein with appendage. Length 4.5 mm. 



Described from Mexico. 



18. P. appendiculatus n. sp. 



o 71 . Front and face silvery; occiput white. Antennae with second 

 joint black ; third brown, white pilose with long acuminate apex. 

 Mesonotum subopake, more shining and cinereous laterally; brown 

 pollinose; laterally, pleura? and metanotum cinereous. Scutellum 

 opake brownish, with fine marginal hairs ; humeri black ; halteres 

 brown or yellowish. Abdomen subopake to nearly shining, faintly 

 brownish pollinose ; apical margin of first whitish ; lateral angles of 

 following segments cinereous, those of fifth extending dorsad in form 

 of oblique spots; hypopygium moderately developed, a little com- 

 pressed to right, with apical cleft ; intermediate lobe hardly visible ; 

 ventral lobe small, black ; lateral margins of all segments with scattered 

 yellowish pile. Coxae and femora black, trochanters, extreme bases 

 and apices of femora, tibiae excepting median brown rings, tarsi 

 except apical joints and pulvilli, yellow. Femora moderately thick- 

 ened, all with distinct flexor spines ; posterior surface of middle femora 

 with complete series of long yellow hairs, post-tibiae swollen medianly 

 where there are a few long whitish hairs on outer surface ; flexor mar- 

 gin sinuate; apical and basal joints of post-tarsi in proportion 1:2. 

 Wings brownish with brown stigma (Fig. 158). Length, 4.4 mm. ; 

 wings, 6.25 mm. 



9 . Similar. Front entirely silvery except shining spot at vertex ; 



