750 BULLETIN UNITED STATES GEOLOGICAL SURVEY. 



MYCETOPHILIDJE. 



Diadocidiaf terricola. — This species is founded upon a single wing 

 (No. 125) found by Mr. Eicliardson, differing to sucii a degree from Dia- 

 docidia that I only place it here because the only other reasonable course 

 would be to refer it to a new genus, which would necessarily be con- 

 jectural, 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 Biadocidia, 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 5 one of these rows in the costal cell is so 

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

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

 beyond the middle of the wing, a feature apparently unknown in 3Iyce- 

 tojyliilidcBj the first longitudinal vein terminates only a little further 

 beyond, and, as in Diadocidia, there is no transverse vein connecting 

 them ; the second longitudinal vein terminates a little above the apex 

 of the wing, curving downward at its extremity and apparently sur- 

 passed a little by the marginal vein; the third longitudinal vein origi- 

 nates 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 perpendicular 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, which, 

 beyond this point, has a gently sinuous course, and diverges rather 

 strongly from the fourth ; the sixth, vein cannot be traced, although the 

 axillary field is broad, very much as in Diadocidia, and the inner margin 

 distinct. 



Probable length of wing 3.6"""; its breadth 1.45""". 



SacTicnia sp. — l!fo. 7 of Mr. Eichardsou's collection represents a species 

 of Mycetophilidw apparently belonging to this genus, so far as can be 

 determined. It closely resembles Saclienia arcuata Scudd. from the 

 White River shales, but differs from it in its smaller size and in possess- 

 ing a proportionally larger and more arched thorax ; the legs also appear 

 to be shorter. Besides the body and (indistinctly) the antennae and legs, 

 only the upper j)ortion of the wings remain, consisting of the costal 

 margin and first and second longitudinal veins, with the cross vein 

 uniting them ; these wholly agree with the same features in S. arcu- 

 ata, excepting +hat the second longitudinal vein terminates a little 

 higher up. 



Length of body 3.75'"", of wings 2.9'"™. 



Three other species of Mycetopliilidw occur among the specimens col- 

 lected by Mr. Bowditch and myself, but they are indeterminable from 

 their fragmentary condition. One of them, No. 4134, has indeed the 



