DIPTEEA. 255 



A variable species, as regards the colour-markings of the abdomen. Bellardi had 

 but a single poorly-preserved female example for his description of P. incerta, which 

 description, so far as it goes, applies well to the insect before me. The specimens 

 that Bellardi described as P. nigronotata, var., do not seem to differ from some of these. 

 In the present collection there are eighteen specimens, which may be described as 

 follows : — 



S . Frontal triangle and face brownish-yellow, lightly covered with yellowish dust. First two joints of the 

 antennae yellow ; third joint yellowish-red, the first annulus disciform, the others slender, the last as 

 long as the five preceding together. Palpi yellow, with black hairs. Mesonotum, except the lateral 

 margins, black in ground-colour, which is concealed beneath a dense yellowish-grey dust and yellowish pile. 

 Abdomen yellow ; fourth, fifth, and sixth segments black, greyish-dusted, and with the hind margin 

 lighter-coloured ; second segment with a median, triangular, black spot, sometimes small, at other times 

 of considerable size ; third segment usually with a small median spot of the same colour. Legs brown, 

 the femora black ; the four front tibiae and tarsi yellow or yellowish. Wings tinged with brown, more 

 so anteriorly ; first posterior cell closed ; second submarginal cell appendiculate. 



2 . Front rather narrow, a little wider and not at all prominent below. Abdomen sometimes wholly yellow, 

 except the distal two or three segments ; at other times the first and second segments are yellow, with a 

 large black spot in the middle, the other segments black, with a narrow yellowish hind-margin. Legs 

 sometimes wholly yellow; at other times dark, as described for the male. Length 11-15 millim. 



CHRYSOPS (p. 45). 



l (a). Chrysops virgulatus. 



Chrysops geminatus, Macq. Dipt. Exot., Suppl. iv. p. 39 l (nee Wiedem.). 

 Chrysops virgulatus, Bellardi, Saggio, etc. i. p. 71, t. 2. fig. 17 a . 

 Chrysops crassicornis, v. d. Wulp, Wien. ent. Zeit. iii. p. 141 3 . 



Hob. Mexico, Guanajuato (Duges 3 ), Cuautla (Saussure 2 ), Guadalajara and Santiago 

 Iscuintla in Jalisco (Schumann), Amula and Chilpancingo in Guerrero (H. H. Smith). 



Seven specimens. Bellardi 2 imperfectly described the* male. It has the antennae 

 yellow or brownish-yellow, with the narrowed portion of the third joint black ; the 

 first joint is very much swollen, the second is a little shorter than the first and also 

 much swollen, the third not longer than the second, broad on its basal part, narrow on 

 the distal part. This peculiar structure of the male antennae, together with the narrow 

 separation of the eyes and the prominent facial tubercles, will readily distinguish the 

 species. In the female the first basal cell has a square hyaline spot ; the second basal 

 cell has the proximal third and the tip brown, and the anal cell is brown only at the 

 distal end. Both sexes have a triangular hyaline spot in the fifth posterior cell. 



C. virgulatus was not identified by Osten Sacken (antea, p. 59). 



Chrysops costatus (p. 46). 



Chrysops costatus, Townsend, Ann. & Mag. Nat. Hist. (6) xix. p. 18 (1897) 1 . 



To the localities given, add : — Mexico, San Rafael in Vera Cruz (Townsend l ), Teapa 

 in Tabasco (H. H. Smith). 



