ART 18 DIPTEEA OR TWO- WINGED FLIES ALDRICH 13 



MESEMBRINELLA SPICATA, new species 



Male. — Purplish-black in color, only the palpi, face, anteni:ae 

 and lower part of front bright j'ellow. Front wide for a male, 0.115 

 of the head width by micrometer (one specimen), the frontal rows 

 composed of delicate hairs to the middle, below about 7 larger, the 

 lowest just below antennal insertion ; ocellars large, proclinate, !a pair 

 almost as large behind the triangle; vertical only one pair. Third 

 antennal joint more than three times the second ; facial ridges rather 

 high and sharp, hairy almost to the middle of the third antennal 

 joint; bucca one-fifth the eye height. 



Mesonotum not with distinct pollinose stripes. Chaetotaxy : doi- 

 socentral 2, 3 ; acrostichal 2, 1 ; humeral 3 ; posthumeral 2 ; presutural 

 1; notopleural 2; supraalar 3; intraalar 2: postalar 3; scutellar 2 

 lateral, 1 large apical, 1 large discal; sternopleural 2. Pleurae con- 

 colorous with mesonotum. Calypters transparent with black rim 

 and conspicuous black fringe. Both thoracic spiracles large, dark. 



Abdomen purplish-black, with rather dense, erect, short hair, no 

 bristles whatever. Genital segments large and conspicuous, shining 

 black; inner forceps shining black, parallel and close together, not 

 tapering, blunt at tip, the base behind united and swollen into a 

 sudden hump which is paler in color, divided into two arms back- 

 ward toward the anus, and these arms bear a pair of black, converg- 

 ing processes ending in tufts of black hair which touch each other on 

 the middle line. Outer forceps shining black, twisted, blunt. Fifth 

 sternite narrow, shining black including its sides, with two erect, 

 blunt, shining black processes in the place of the usual lobes. 



Legs blackish; middle tibia with flexor bristle; hind tibia with 

 long calcar just below middle. 



Wings subhyaline, small cross vein inf uscated ; the opening of the 

 apical cell at costa is about one-fifth the preceding costal segment. 



Length 8.3 mm. 



Described from one male. La Suiza de Turrialba, Costa Rica, 

 Februaiy 22, 1923 (Pablo Schild). Through the kindness of Prol 

 A. L. Melander we retain this striking unique for the United 

 State National Collection. 



Ty/^e.— Male, Cat. No. 26796, U.S.N.M. 



MESEMBRINELLA UXISETA, new species 



A blue-black species with face, antennae, palpi, and thoracic spi- 

 racles yellow. 



Male. — Front rather wide, 0.13 the head width (the same in three 

 specimens measured by micrometer), black to antennae; no frontals 

 of any size above the middle ; ocellars long, proclinate, a post-ocellar 

 pair also long; only one moderate pair of verticals. Third antennal 



