14 AMERICAN BLACK FLIES OR BUFFALO GNATS. 



turn is also preoccupied by a species recorded by Lugger,^ and I pro- 

 pose for this species the name lutzi.^ 



TABLE OF GENERA. 



1. Basal joint of hind tarsus generally distinctly prolonged, lappet-like, on 



posterior surface at apex ; second joint witli basal scale-like i)rocess and 



dorsal excision; radial vein unforked; basal cell absent SimuHum. p. 25. 



Basal joint of bind tarsus generally but little produced at apex pos- 

 teriorly; second joint linear, without basal scale or dorsjil excision; 

 radial vein generally with elongate fork 2 



2. Face broad; basal cell of wings distinct ProsimuUum, p. 15. 



dorsal excision; radial vein unforked; basal cell absent 8imuUum,\).25. 



TABLE OF LARVJE, 



The following table of larvae has been arranged to include all the 

 species dealt with in this paper which have been associated with the 

 adults. 



1. Labium with the central tooth trifid 2 



Labium with the central tooth simple 3 



2. Only the central labial tooth trifid /*. pecnarum, p. 23. 



All teeth except the outer one on each side more or less irregularly 



trifid P. hirtipes, p. 10. 



3. Anal blood gills simple, three in number 8. iHttatum, p. 55. 



Anal blood gills subdivided 4 



4. Large species (10-12 mm. in length), almost black in color. 



S. jnctipes, p. 57. 

 Smaller larvae, generally yellowish in color, with more or less distinct 

 cross-bands to segments 5 



5. Last joint of maxillary palpus without setfe S. mericUonale, p. 51. 



Last joint of maxillary palpus with setse 6 



6. Labium with seven pairs of setae on ventral surface S. piscicidium, p. 4G. 



Labium with less than seven pairs of seta; 7 



7. Labium with four pairs of setse 8. jenningsi, p. 42. 



Labium with five pairs of setse S. venustum, p. 44. 



The foregoing table is partly constructed from that given by 

 Johannsen in his paper on the group. It is probable that there are 

 groups, instead of single species, with the characters given in this 

 table and in the table for the pupae (p. 15), but until some one with 

 the necessary knowledge of the anatomy of the larvae and pupae de- 

 votes considerable time to their study our knowledge must remain 

 fragmentary' and unsatisfactory. It is also probable that there are 

 some species which are not possessed of tangible distinctions in the 

 imago stage which may be easily separated in either the larval or 

 pupal stage. 



1 Bui. 48 Minn. Agr. Exp. Sta., 1896, p. 202. 



-The manuscript of thiK paper was completed in December, 1912, but has l)ei'u delayed 

 in Its appearance in print frora various causes. In the number of " Insecutor Inscitloe 

 Menstruus " for December, lOl.S, there appears a note on American SlmulUdae, which 

 deals with certain matters referred to in this and preceding pages. The writer of the 

 note referred to was cognizant of the existence of this manuscript, and conversant with 

 its contents, which I consider do not accordingly require any alteration due to the appear- 

 ance of said note. 



