22 Mr. C. H. T. Townsend on Dipfera 



is more or less black pile luixed vvitU the yellow on frontal 

 triangle. First abdominal segment silvery whitish in 

 middle. Linear brown stripe of second and third segments 

 ahnost obsolete. There is hardly any dark anterior margin 

 perceptible on second segment. Tlie third and fourth seg- 

 ments are the same colour as tlie second, but they each have 

 an entire shining cross-band which the second lacks. Fifth 

 segment black. Legs rather deep reddish yellow, with 

 proximal half of middle and front tibiae yellowish white. 

 Hind femora narrowly and faintly brownish on distal ends 

 above. Tarsi wholly reddish yellow, distal half of foot- 

 claws black. Wings pure hyaline, except a small well-defined 

 subquadrate dark brown or blackish spot at end of auxiliary 

 vein, between latter and first vein. Wing-veins pale yel- 

 lowish. Tegulai light buff-yellow, -with a fine long yellow 

 silken fringe on border j alulets faintly fuscous, with a ciliate 

 black fringe. 



10. Meromacrus crucigeruSj Wied. 



Seven males and five females, San Rafael. A small 

 female, March 16 ; the others July 1 to 18, on flowers of 

 the Cordia sp. 



Length II5 to 15 millim. 



The ground-colour of the small female taken in March is 

 black, except two reddish oval lateral spots on second seg- 

 ment anteriorly. In this specimen also the facial stripe and 

 frontal vitta are more or less blackish. All the others belong 

 to the form mentioned by AVilliston in the Biol. Centr.-Amer., 

 Dipt., from Sonora and Teapa. The ground-colour of 

 abdomen is reddish brown, hind femora blackish or brown 

 except at distal end. Two of the females (July i) and 18) 

 have the posterior segments of abdomen a little darker, and 

 all of the four females taken in July have the frontal vitta 

 blackish only on posterior two-thirds. They all, however, 

 as well as the males, have the facial stripe reddish. Frontal 

 triangle in the males, and anterior one third of frontal vitta 

 in the females, reddish. In all the males except one the 

 pile on sides of frontal triangle is whitish instead of yellow. 

 Pile of sides of front and face in female very deep yellow, 

 like the pile of thoracic and abdominal markings. These 

 latter markings agree perfectly with Williston's description 

 (Syn. p. 180). Middle of first abdominal segment, and 

 narrow concave front border of second, opaque black. A 

 more or less distinct blackish tinge to other segments, 

 leaving a pair of large reddish lateral lunate triangles on 

 second segment. 



