DII'TKUA MYCETOPHLLIl >.!:. 595 



they divide near the center of tlie wing, ;nnl tin- tilth and sixtli longitudinal 

 as near the base as the third and fourth; tin- sixth longitudinal vein is 

 strain-lit, and appears to reach the margin of the wing. 



The gemis resembles Boletina more than any of the genera figured by 

 Winner!/,, but diH'ers strikingly from it in the approximation to the base of 

 the forking of the third and fourth, and of the fifth and sixtli longitudinal 

 veins. In this particular it closely resembles the Sciarina, but on the other 

 hand differs from them to a greater degree in the length of the auxiliary 

 and first longitudinal veins, and in that the former reaches the cqsta. The 

 costal vein does not appear to pass beyond the tip of the second longi- 

 tudinal vein, but this point is obscure. 



I have dedicated this genus to the distinguished dipterologist, Baron 

 ( )sten Sackeii, to whom 1 am indebted for many suggestions in the deter- 

 mination of these fossils. 



SACKENIA ARCUATA. 

 I'l. 5, Figs. 3, 4, 12, 13. 



Sackenia arcuata Sctulil., Bull. U. S. Geol. Geogr. Surv. Terr., Ill, 754-755 (1877) ; in Zitlr), Hamlli. <1. 



PaliBont., I, ii, 811, Fig. 1088 (18*5). 



This species is represented in part by a female specimen, more than 

 usually well preserved. The body is pale testaceous; the wings wholly 

 hvaline, lint the veins faint testaceous; the antenna; are a little longer than 

 the head and thorax together, very slender, of the color of the thorax: the 

 ba>al joints are snbglobular, slightly broader than long, the remainder twice 

 as long as broad, and beyond the middle of the antennas slightly monili- 

 form. In the wings, the base of the hinder cell, using Winnertz's terminology, 

 lies within the base of the upper discal cell, both being nearer the base of 

 the wing than the middle transverse vein, while the base of the middle dis- 

 cal cell is far outside of either of these, near the center of the wing. The 

 costal vein appears to terminate where the cubital reaches the margin, and 

 the axillary vein nearly or quite reaches the bonier. The legs are partly 

 detached, and the basal portion of the front pair obscure, but it look* as 

 though the front tarsi were about three times as long as the front tibiae, 

 which is hardly probable. 



Length of lio.lv. f>.i:.Y"" ; antenna?, 'l mm ; win^s, I. _'.">""": hind femora, 

 :;"""; hindtibiie. 2 min ; hind tarsi. 2.4 ; fore tarsi, L' 



