314 



spicuous fringe; abdomen of male usually with 5 or 6 segments 

 in addition to the hypopygium ; metallic greenish or bluish 

 species, usually with fleshy proboscis. . . Dolichopodidae (p. 403). 



Tribe Platygenya 



The larvae of members of this tribe are distinguished from those 

 of Orthogenya by the structure of the head, the plates forming it be- 

 ing flat and straight, when not enclosed within a conical chitinized 

 capsule, and lying on a horizontal plane when at rest. Occasionally 

 the exposed portion of the head is heavily chitinized on the anterior 

 half, forming a cone from whose small apical opening the mandibu- 

 late processes protrude. 



I am unable to give characters for the differentiation of the pupae 

 of this tribe from those of Orthogenya, the species of the latter known 

 to me being so few that a generalization based on them would prob- 

 ably prove misleading. 



This tribe contains all of the Brachycera except Dolichopodidae 

 and Empididae. Characters for the separation of these families will 

 be found in the preceding key to different stages. 



Superfamily Stratiomyioidea 



SUPERFAMILY CHARACTERS 



The family Acanthomeridae is confined to tropical America and is 

 unknown to me, but the other three families are represented in all 

 stages in my material. 



Larva. — Head with the anterior half cone-shaped, permanently 

 exserted, in Xylophagidae and Cecidomyiidae heavily chitinized. the 

 mandibulate processes protruded through a small opening in the apex. 

 The larvae of Stratiomyiidae have the head less heavily chitinized 

 than do those of the other two families known to me in that stage, 

 but the anterior half is non-retractile — a character which separates 

 these larvae from those of other superfamilies. Manv of the genera 

 have distinguishable spiracles on metathorax and abdomen which are 

 probably not functional. For other distinguishing characters see key 

 to larvae of Brachycera and descriptions under family headings. 



Pupa. — The pupae of Stratiomyiidae are enclosed within the last 

 larval skin — a fact which separates them from other Brachycera. The 

 pupae of Xylophagidae and Coenomyiidae are free, and differ from 

 those of other Brachycera known to me in having the antennae with 

 well-defined annuli. 



Imago. — See key to imagines of Brachycera. 



