SOME AMERICAN FOSSIL INSECTS. 



By T. D. a. Cockerell, 

 Of the University of Colorado, Boulder. 



The insects described in this paper range in age from the Coal 

 Measures to the Miocene. Perhaps the most interesting is a new 

 species of DolopMlus^ the first insect to be described from American 

 amber. Second in interest is Hypoderma ascarides (Scudder), rep- 

 resented by larvae and pupae, which are sufficiently numerous and 

 well preserved to leave no doubt that they belong to the Oestridae, 

 and were parasitic on some mammal. Two Coleopterous elytra repre- 

 sent a new Eocene locality for fossil insects in North Park, Colorado. 

 A gall on narrow-leafed cottonwcrod from Florissant appears to have 

 been made by a beetle of the genus Saperda. 



The majority of the Florissant insects described were received 

 through Mr. F. H. Ward, of Rochester, New York, who obtained them 

 from Mr. G. W. Wilson of Florissant, whose ranch had previously 

 yielded many new species of fossils. It is a pleasure to record a new 

 genus from the Mazon Creek Carboniferous, collected by Mr. L. E, 

 Daniels, who has done so much to increase our knowledge of the 

 Carboniferous land fauna. The insects not indicated as being in the 

 National Museum and in the museum of the University of Colorado. 



DIPTERA. 



PLECIA WOODRUFFI, new species (Bibionidae). 



Wing 7 mm. long, 2.75 broad. Costal region suffusedly dusky. A 

 relatively broad-winged species of ordinary type, somewhat remark- 

 able because the anterior cross vein is shorter than the distance from 

 its lower end to the basal corner of the second posterior cell. Second 

 posterior cell on upper side about 2.8 mm. long; submarginal cell 

 about 1.9 mm. long; outer side of anal cell not much elbowed. 



Green River Eocene, east side of Evacuation Creek, near Ute Sta- 

 tion, Utah (E. G. Woodruff). The species is represented by a single 

 wing, on the underside of a rather thick slab of shale on which are 

 many larvae of Hypoderma ascarides. This species is smaller than 



Proceedings U. S. National Museum, Vol. 51— No. 2146. 



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