2 PROCEEDINGS OF THE NATIONAL MUSEUM. vol. 63- 



cept in some specimens of the subgenus Phorocera; pteropleural 

 bristle small or absent. Abdomen black or gray, never metallic green, 

 with macrochaetae but never with more than three pairs on middle of 

 second tergite. Wings with normal venation, first posterior cell 

 (apical) open, rarely closed in margin, ending considerably before 

 apex of wing ; last section of fifth vein never half as long as preced- 

 ing; veins bare except base of third. 



Absence of j)eculiar characters may be said to distinguish this 

 group; if we add to it a similar series not very well separated in 

 which the eyes are bare, the combination will comprise a vast central 

 mass of the family Tachinidae in the wide sense, from which other 

 genera or groups of genera seem to radiate in all directions by the 

 development of peculiar characters. Naturally this central mass is 

 the difficult part of the family, the outlying groups having their spe- 

 cial characteristics which have greatly facilitated their classification. 



We have included a number of tropical species, although our work 

 must be very incomplete in that direction. We have not attempted 

 the profitless task of discussing the probable identity of those spe- 

 cies of earlier writers that we can not recognize, preferring to leave 

 them to be elucidated from the types at some future time. Van der 

 Wulp's Biologia types are in the British Museum, and those of Bigot 

 are in the collection of J. E. Collin, of Newmarket, England; it is 

 only a question of time until these are studied by a competent au- 

 thority, and this will for the first time put the tropical North Ameri- 

 can fauna upon a sound basis. 



Many new and unpublished rearing records have been added, and 

 scattered ones have been gathered together ; thus the economic aspect 

 of the group has been appreciably clarified, although much remains 

 to be done in the biological study of it. The criticism may be made 

 that our classification does not sufficiently reflect the biological char- 

 acters that have been made known in the last ten or fifteen years. 

 We have given serious consideration to this anticipated objection. 

 It is a difficult matter to assign taxonomic values to internal charac- 

 ters, and especially to physiological peculiarities. We should feel 

 under greater obligations to attempt the task, if it were not for the 

 fact that in 85 per cent of our species nothing whatever is known 

 about these characters. 



TABLE OF GENERA. 



1. Facial ridges with stout bristles at least up to middle 2 



Facial ridges bristly at most only on lower third, rarely with weak 



bristles or hairs above this 6 



2. Penultimate joint of arista at least three times as long as thick 5 



Penultimate joint of arista hardly longer than thick (Phorocera Robi- 



neau-Desvoidy). 3 



