216 A. L. MELANDER. 



Platypalpus trivialis Loew (Figs. 26, 34, 43). 

 Cent. V, 76. 



Two males among a lot of Plaiypalpiis taken by Dr. Garry de N. 

 Hough on June 12th at New Bedford, Mass., are presumably asso- 

 ciated with a large female taken at the same time. The female is 

 evidently the same form as was described by Dr. Loew as trivialis. 

 If these males are the other sex of trivialis, we have another case of 

 great sexual dimorphism. 



Male. — Length 3.5 and 4.5 mm., wings same. Middle and front femora black, 

 except apical fourth ; front femora ciliate, with long while hairs beneath ; front 

 coxae black, middle ones piceous, hind ones dusky; front tibise even larger than 

 in the female; scutellar bristles rather small in comparison with the size of the 

 species; humeri more conspicuous than usual; hypopygium not large, rounded, 

 with a small stiff fringe of yellow hairs on the left side; under side of second 

 basal cell strongly sinuous; first posterior cell quite wide in its third quarter; 

 costa thickened at insertion of first vein. 



The male differs from pachycnemus Loew in being double the size. 

 Aside from the following points the description of pachycnemus will 

 answer for this species : 



Antennae black ; posterior femora wholly yellow ; anterior femora 

 strongly incrassate ; tibise wholly yellow ; tarsi yellow, apex of each 

 joint sharply black, the amount of black increasing on the distal 

 joints ; anal vein rather strong. 



The front femora of the female of trivialis are not ciliate, the 

 other femora not blackened, and the second basal not strongly 

 sinuous. 



D. C, Maine (O. Sacken). 



Mr. Coquillett claims to have received this species from Santa Fe, 

 New Mexico, from Mr. Cockerell. 



Platypalpiis caligalus sp. uov. (Figs. 27, 35, 46). 

 The discovery of the male of trivialis shows that the insect men- 

 tioned in the Biologia Centrali- Americana as related to trivialis 

 must be a distinct form. The points of difference are : 



Male. — Length 3 mm., wing 5 mm. Legs, including coxae, yellow, front 

 femora and tibiae less thickened ; cilia of lower occiput, coxae and femora shorter 

 and fewer in number; tarsi not annulate; scutellar bristles black; hypopygium 

 smaller and with a longer yellow fringe on left side ; venati(m weaker, underside 

 of second basal straight; sides of first posterior cell less sinuous, anal angle less 

 prominent. 



Female. — Size of body and of wings as in male. Tarsi not annulate ; thoracic 

 macrochaetae black ; anal angle rounded, third and fourth longitudinals less 

 sinuous. 



