16 PROCEEDINGS OF THE NATIONAL MUSEUM vol. 66 



MESEMBRINELLA FLAVICRURA, new species 



Blue-black, the following parts yellow: Front except upper half 

 or less, antennae, face, bucca, palpi, humeri and lower prothoracic 

 region, thoracic spiracles, first abdominal segment in large part in 

 the male (less in the female), coxae, all the femora except the tips. 



Male. — Eyes almost contiguous, the front at narrowest onlj' as 

 wide as the anterior ocellus ; the rows of frontal bristles begin below 

 the narrow part; ocellars and post-ocellars of equal size, not large; 

 verticals small. Facial ridges quite flat, only a few hairs above 

 vibrissae; bucca one-fifth the eye height. 



Thorax not with distinct pollinose stripes. Chetotaxy: dorso 

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

 notopleural 2; supraalar 3; intraalar 2; postalar 3; scutellum with 2 

 lateral, 1 apical, 1 discal. Calypters infuscated, especially the pos- 

 terior, with dark rims. Spiracles large, yellow. 



Abdomen bluish-purple, the first segment yellow except a narrow- 

 black posterior border above and below which widens suddenly at 

 the sides ; second segment with trace of yellow above anteriorly. The 

 first segment has one small lateral marginal, the second a large one, 

 the third and fourth a marginal row, no discals. One male has a 

 small but unmistakable pair of median marginals on the second 

 segment. 



Legs black except as indicated, middle tibia with flexor bristle, 

 hind tibia with large calcar below middle. 



Wings lightly infuscated, paler toward base ; small cross vein de- 

 cidedly infuscated; fourth vein and apical cell as in uniseta. 



Female.— Fmnt 0.23 of headwidth (average of three, 0.22, 0.24, 

 0.24); two pairs of orbitals; only one vertical. First abdominal 

 segment varying in amount of yellow, sometimes with much less than 

 indicated for male. 



Length of males, 7 and 7.8 mm. ; of females, 8 to 8.5 mm. 



Described from two males and five females, La Suiza de Turrialba, 

 Costa Rica, February 8 to July 26, 1923 (Pablo Schild). In Prof. 

 A. L. Melander's collection. 



Paratypes.—lA?i\^ and female, Cat. No. 26800. U.S.N.M. 



Tribe CHRYSOMYIINI 



TABLE OF GENERA OF THE WOELD 



1. Hind calypters covered with hairs on upper side (Eastern Hemisphere 



except Chrysomyia desvoidyi Hough, noted below) 2 



Hind calypters bare except in the basal depression (Western Hemi- 

 sphere) ^ 



2. Vibrissae at least the length of the second antennal joint above oral 



margin (type, marginalis Fabricius) Chrysomyia Robineau Desvoidy. 



Vibrissae at oral margin; male with broad front; small Australian species 

 (type, varipes Macquart) Microcalliphora Townsend. 



