Biptera of St. Vincent {West Indies). 305 



varies much. There are no structural differences in any 

 of the specimens, and, in some of the San Dominican 

 specimens, the colour of the bristles of the hind femora 

 varies. Taking the above facts into consideration, I 

 believe that all the names above given, and probably 

 others, represent a single species of wide distribution. 

 0. tibialis occurs through all of the Eastern United 

 States, as far as the Rocky Mountains. 



Ersx. 



Macquart, Dipt. Exot., i., 2, 107, 1838. 



1. Erax rufitihia. (PI. X., fig. 79, wing.) 



Erax rufitihia, Macquart, Dipt. Exot., 3rd Suppl., 27. 

 PI. ii., fig. 11 ; Walker, List, vii., 623 ; Roeder, 

 Stett. Ent. Zeit., 339, 1885. 



Hah. Brazil; San Domingo; Porto Rico. 



$. Front and face light yellowish-grey ; gibbosity of the face 

 "with numerous black bristles and yellowish-white hairs. Mesono- 

 tum grey, with three broad black stripes, narrowly separated, the 

 lateral ones narrowly divided into three spots, the hindmost one 

 of which is small ; the middle one with an indication of a middle 

 stripe in front. Abdomen black, not shining ; hair yellow, sparse 

 and reclining, save on the anterior two segments ; lateral margins 

 opaque light-grey ; sixth and seventh segments silvery ; hypopy- 

 gium large, black. Wings with the costal border thickened ; 

 furcation of third vein beyond the base of the second posterior cell. 

 Legs black ; tibite except the tip, red. Length 18-20 mm. 



Two males and three females, the latter showing 

 scarcely any differences, save the usual sexual ones. 



Leptogaster. 



Meigen, Illiger's Mag., 1803. 



1. Leptogaster roederi, n. sp. (PL XL, fig. 80, wing.) 



^ , $ . Antennfe yellow, with the distal half of the third joint 

 black; wings blackish at the tip. Length 8-9 mm. 



Front brown. Face and mystax yellow. First two antennal 

 joints and the base of the third yellow ; remainder of the third 

 joint and the arista black ; third joint a little shorter than the first 

 two together, the arista a little longer than the three joints 



