NO. 2146. SOME AMERICAN FOSSIL INSECTS— COCKERELL. 91 



terior cell on wing-margin, 960; fifth posterior cell on wing-margin, 

 1,120. 



Miocene shales of Florissant, Colorado, Station 14 (George N. 

 Rohwer). The abdomen is like that of Pachygaster maculicornis 

 Hine (determined by Malloch), which I collected on the campus of 

 the University of Colorado, Boulder, on June 30. The venation dif- 

 fers from Pachygaster^ and agrees better with that of Oxycera^ of 

 the section having the cubital vein forked. The insect is peculiar for 

 the very long discal cell, and the veins leaving it dark and distinct 

 to the wing-margin; in these respects it is more primitive than the 

 living species of Oxycera of which I have any knowledge. 



HYPODERMA ASCARmES (Scndder). 

 Plate 2, figs. 4, 6, 7. 

 Musca ascarides Scuddek, Tertiary Insects of North America, 1890, p. 551. 



Larva large and robust, fully 30 mm. long and 8 broad, formed as 

 in the modern 11. h'neata, each segment with a transverse row of 

 tubercles beset by minute bristles, the lateral tubercules inclined to be 

 prominent, as in II. hovis. Pupa about 11 mm. long and 6 broad, 

 very dark, with strong lateral spinuliferous tubercles marking the 

 segments. The details are best shown by the figures ; «, caudal end 

 of larva, with spiracles and tracheal tubes; &, three segments of mid- 

 dle of larva, showing spinuliferous areas ; c, lateral projecting spinu- 

 liferous area of a larva beginning to contract; d^ spinuliferous areas 

 of another larva ; e, mandibles of larva ; /, lateral spinuliferous pro- 

 jections of semipupa ; g, contracted and hardened pupa. 



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

 tion, Uintah Railway, eastern Utah (E. G. Woodruff). 



Plesiotypes.—C?it. No. 61457, U.S.KM. 



The specimens are very numerous, in all stages between the freshly 

 dropped larva and the hardened pupa. Considering their age, they 

 probably represent an extinct genus of Oestridae, which appears to 

 differ from Ilypoderma by the prominent lateral tubercles of the 

 pupa, more after the manner of C ephalomyia.. In the absence of the 

 adult fly, however, it seems undesirable to remove the species from 

 Ilypoderma. 



Scudder'^ remarks that the specimens of Musca ascarides " so closely 

 resembles the larvae of bot flies that I could scarcely persuade myself 

 that they did not belong to the Oestridae. The appendages of the 

 skin, however, are much more delicate than is usual in Oestridae, and 

 are uniformly distributed over the surface or are altogether absent." 

 The more complete material now before me shows that the spinules 

 or minute bristles are not uniformly distributed over the skin, but are 



1 Tertiary Insects of North America, 1890, p. 551. 



