16f AMERICAN BLACK FLIES OR BUFFALO GNATS. 



deductions are correct with regard to the formation of the cocoons 

 of this genus, but on the other hand some of the species which are 

 unknown in the early stages may have habits similar to Slmulium 

 Latreille, and I therefore do not make use of them, preferring to use 

 the characters furnished by the venation of the wings,^ which was 

 not mentioned b}^ Roubaud in dealing with the group, as well as 

 those of the hind tarsus. 



As I have already pointed out, in dealing with the larval charac- 

 ters, it is not improbable that the labium of the larva? may provide 

 a further character for the separation of this genus from Simulium, 

 though that, like the character of the cocoon formation, requires 

 further study before being accepted as a generic rather than a specific 

 character. 



Roubaud states that the claws in Prosimulium are all of one type, 

 "very simple," and also that the species are confined to "high alti- 

 tudes or cold regions." These statements are not in accordance with 

 the actual facts of the case, as he included pecuarum Riley, which 

 has bifid claws, and was originally described from Louisiana, as one 

 of the species in his original definition of Prosimulium. It is always 

 risky to generalize upon insuificient data or material, and though I 

 possess probably a much larger amount of material than Roubaud 

 had, I consider that I have gone as far as my material justifies me 

 in separating the genera by the characters given in my table and in 

 indicating the probable significance of others without giving them 

 as generic distinctions. 



GENERIC CHARACTERS. 



Eyes in male large, meeting above, the upper facets much larger 

 than the lower and separated by a horizontal line ; in female the eyes 

 are separated by a wide and more or less divergent-sided stripe. 

 Antennae 11-jointed; palpi 4-jointed. Wings with the radial vein 

 furcate, or indistinctly so, or simple (mutatum), and a small, closed 

 cell near wing base (PI. I, fig. 3). Hind tarsi with apex of first joint 

 very slightly produced posteriorly, except in mutatum, and second 

 joint linear (PI. II, figs. 1, 2) ; tarsal claws tridentate in male, in 

 female simple (PI. II, fig. 13), or with the base produced thumblike 

 (PL II, figs. 14,16). 



Type of genus. — Shnulium hirtipes Fries. 



TABLE OF SPECIES. 



L Eyes widely separated above (females) 2 



p]yes closely coherent above (males) 6 



2. Tarsal claws with base produced into an elongated projection, bifid 3 



Tarsal claws with base only slightly tuberculate or rounded, simple 4 



1 1 havo included in this fjonus mufaium, which has the radius simple, and pecuarum, 

 which has it vory indistinctly furcate, preferring to retain the former here instead of 

 erecting another genus for it. 



