THE ORIENTAL TRIGONOMETOPINE FUES 131 



belong to stretchii, as venusta is not known in Porto Rico. In regard 

 to the specimens cited above as having lost the black dots and bands and 

 become indistinguishable horn ornatrix, it is possible that they are that 

 species, and that two species occur in Porto Rico, ornatrix by way of 

 the Lesser Antilles, from continental South America, stretchii as an off- 

 shoot of Venusta of the Greater Antilles, more remotely from bella of 

 continental North America. The breeding of the two forms by local 

 workers v«ll decide. 



THE ORIENTAL TRIGONOMETOPINE FLIES 



(^Diplera, Lauxaniidct) 

 By FREDERICK KNAB 



Until recent years species of Trigonometopus were known only from 

 Europe and America. Prof. Hendel, in 1 909, was the first to describe 

 a species from the Oriental region — Trigonometopus monochata from 

 Formosa.^ Since then four other species have been described, hrevicor- 

 rns de Meijere from Java,^ trilineatus Brunetti from Assam,^ alhiseta 

 Bezzi and bakeri Bezzi from the Philippines.* An additional species 

 from the island of Guam is characterized herein. 



The species described by Hendel and Brunetti differ from typical 

 Trigonometopus in a number of striking characters and may be segre- 

 gated as follows : 



Diplochasma, new genus. 



Closely related to Trigonometopus and differing from it as follows : 

 Only one pair of fronto-orbital bristles; postvertical bristles wanting. 

 Face but moderately receding in profile, the clypeus strongly projecting 

 and extending upwcird on the face to base of antennae, sinuate in outline 

 when seen in profile. 



Type, Trigonometopus monochata Hendel. 



Brunetti's Trigonometopus trilineatus is congaieric, closely resembles 

 monochata, and may be a s)Tionym of it. The only tzuigible difference 



•Wien. Ent. Zeit.. vol. 28. p. 85, 1909. 



^Tijdschr. V. Ent.. vol. 54. p. 352. 19H. 



s Records Indian Mus.. vol. 8. p. 175; pi. 6. fig. II. 1913. 



*Pha. Journ. Sci.. ser. D. vol. 8, pp. 317. 318. 1914. 



