598 TERTIARY INSECTS OF NORTH AMERICA. 



short, not more than half as long 1 as the middle cell (here again the plate 

 is inaccurate), and the lower discoidal vein forks, apparently, before the 

 base of the upper discoidal stalk, but this point is obscure ; the brevity of 

 the latter is remarkable for a Sciophila. 



Length of wing (estimated), 5.5 nim ; breadth, 2 inm . 



Named for my learned friend and comrade, Prof. Alpheus Hyatt, of 

 Cambridge. 



Green River, Wyoming. One specimen, No. 99 (Prof. L. A. Lee). 



DIADOCIDIA Ruthe". 



DlADOCIDIA ? TERRICOLA. 



PI. 10, Figs. 10, 11. 

 Diadocidia f terricola Sciuld., Bull. U. S. Geol. Geogr. Sure. Terr. IV, 750 (1878). 



This species is founded upon a single wing found by Mr. Richardson, 

 .differing to such a degree from Diadocidia that I place it here only because 

 the only other reasonable course would be to refer it to a new genus, which 

 would necessarily be conjectural, from the imperfection of the fragment. 

 If a transverse vein exists in the middle of the wing, it must unite the 

 fourth longitudinal vein with the second, and not, as in Diadocidia, with the 

 third. The wing itself is shaped much as in Diadocidia, and, at least near 

 its costal border, is covered with fine hairs arranged in rows parallel to the 

 course of the neighboring veins; one of these rows in the costal cell is so 

 distinct as to appear like a vein parallel to and lying within the auxiliary 

 vein. The auxiliary vein terminates in the costal margin far beyond the 

 middle of the wing, a feature apparently unknown in Mycetophilidse ; the 

 first longitudinal vein terminates only a little farther beyond, and as in 

 Diadocidia there is no transverse vein connecting them ; the second longi- 

 tudinal vein terminates a little above the apex of the wing, curving down- 

 ward at its extremity and apparently surpassed a little by the marginal 

 vein ; the third longitudinal vein originates from the second at only a short 

 distance before the middle of the wing, and soon forks, or at about the 

 middle of the wing; the fourth longitudinal vein is perhaps connected with 

 the second at the point where it parts with the first by a cross-vein perpen- 

 dicular to the costal margin ; at least, it is elbowed at this point, its basal 

 portion running parallel to the costal margin to the fifth longitudinal vein, 



