FOSSIL ASILID FLY FROM COLORADO. 213 



are loosely spun together, forming a very slight cocoon-like 

 structure. At first the colour is a translucent yellow-green, 

 palest on the abdomen, which is streaked exactly similar to the 

 larva, each stripe corresponding precisely in form and colour ; 

 all the markings and speckles are pale olive. 



The pupal state occupies about twenty-one days. 



A FOSSIL ASILID FLY FROM COLORADO. 



By T. D. A. Cookerell. 



Cophura antiquella, n. sp. 

 Slender, length to end of fourth abdominal segment, 81 mm. ; 

 wings 6 mm. long and 2 broad, hyaline, without markings, venation 

 extremely pale, but apical half of costa darkened ; head as preserved 

 obtusely subcorneal, not as broad as thorax ; antennae about 640 /a 

 long, the third joint broad and fusiform, its width near base about 

 160 /a ; the part basad of the third joint exhibits what look like three 

 lateral stout processes or pectinations, but these are discordant with 

 the other characters of the insect, and are probably due to imper- 

 fection of preservation ; thorax dark, doubtless black in life ; abdo- 

 men elongate, pallid, with large quadrate dark dorsal patches on the 

 segments, as in the living C. fur (Williston) ; legs pale ferruginous, 

 the tibiae with a very thin, microscopical pilosity ; tibiae long, the 

 anterior ones If mm., the posterior ones about 3 mm., conspicuously 

 longer than their femora, gently broadening (not abruptly swollen) 

 apically ; hind tarsi thick. Venation (measurements in microns) : 

 marginal cell open ; five posterior cells, all open ; anal cell closed a 

 short distance before margin ; venation normal for the genus ; width 

 (depth) of first submarginal cell at level of base of second 430; 

 length of upper side of second submarginal 1760, its apical width 

 530, its width 320, from apex of wing 480 : anterior cross-vein to base 

 of second submarginal cell 1090 ; discal cell on first posterior 800, on 

 second posterior 160, on third posterior 160. 



Miocene shales of Florissant, Station 13 B (Geo. N. Rohiver). 

 Small Dioctria-like Asilidae were evidently common at Floris- 

 sant in Miocene times. The species of this group so far known 

 may be tabulated as follows : — 



Anterior cross-vein about as distant from base of second 

 submarginal cell as the length of that cell (a good 

 character also for recent Dioctria) 



Dioctria florissantina (Ckll.). 

 Anterior cross-vein not nearly so far from base of second 



submarginal cell as the length of that cell . . 1. 



1. Second submarginal cell over 2400 microns long, its base 

 1309 from anterior cross-vein ; anal cell open 



Nicocles miocenicus, Ckll. 

 Second submarginal cell less than 1920 microns long . 2. 



