596 TERTIARY INSECTS OF NORTH AMERICA. 



A second specimen of the same specifts is similarly preserved, but 

 lacks the wings. The legs, however, are better preserved, and show a 

 pair of apical spurs to the tibiae. The antennas are imperfect, but the pro- 

 boscis is seen. The length of the curved body is a little more than 5.5""". 

 The legs are detached and confused, so that it is impossible to separate the 

 middle and hind legs ; one leg (a front leg, to judge from its length) has the 

 following measurements: femur 1.2""°, tibia, 1.4"™, tarsi 1.7"""; another 

 (probably a hind leg): femur 2.1 (?)"^"^, tibia 2.25"'"', tarsi 1.75'°'"; another 

 (probably tlie opposite of the same): tibia 2.25'""', tarsi 1.75"'°'. Appar- 

 ently, all the tarsi are broken. The tibial spines, both in this and the first- 

 mentioned specimen are delicate, and a little more than half as long as the 

 thickness of the tibia^. 



Chagrin Valley, White River, Colorado. Two specimens. (W. 

 Denton.) 



Sackenia ! sp. 

 PI. 5. Fig. 50. 



Another and far smaller species of Sackenia seems to be indicated by 

 the imperfect fragment of a wing and an obscure body. The third longi- 

 tudinal vein is wrongly drawn as if united to the second instead of to the 

 fourth. The common stem of the latter is joined to the second very shortly 

 before their union, this being effected nearer the base of tbe wing than in 

 S. arcuata. 



Length of body, 2"""; probable length of wing, 1.6""". 



Fossil Canon, White River, Utah. One specimen, No. SS" (W. Den- 

 ton). 



Sackenia sp. 



Sackenia sp. Scudd., Bull. U. S. Geol. Geogr. Surv. Terr., IV, 750 (1878). 



A specimen of Mr. Richardson's collection represents a species of 

 Mycetophilidre apparently belonging to this genus, so far as can be deter- 

 mined. It closely resembles Sackenia arcuata from the White River shales, 

 but differs froui it in its smaller size and in possessing a proportional!}- 

 larger and more arched thorax ; the legs also appear to be shorter. Besides 

 the body and (indistinctly) the antennae and legs, only the upper portions of 

 the wings remain, consisting of the costal margin and first and second longi- 



