554 TERTIARY INSECTS OF NORTH AMERICA. 



Length of body, 23 mm ; greatest breadth of same, . t ) m " 1 ; breadth pos- 

 teriorly, 3' m " ; breadth of skin, 9.5 miu ; length of segments on same, 4 mm ; 

 length of mandible blades, 3.5 mm . 



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

 Denton). 



MUSCA VINCULATA. 



PI. 5, Fig. 77. 

 Muaea vinciilata Scudd., Bull. U. S. Geol. Geogr. Stirv. Terr., Ill, 758 (1877). 



There is still another species allied to the last mentioned winch may 

 bear the name here proposed. It is represented only by parts of emptied 

 skins, all lying on the same stone, and which differ from the preceding 

 species in being absolutely devoid of any hairs and in having different and 

 much fainter markings. The general color of the best preserved specimen 

 is a pale brown, and the markings are scarcely darker transverse bands, 

 narrowing on the sides, but occupying nearly the entire length of a segment 

 dorsally, and broken into equal parts by two transverse rows of very faint 

 and minute pale dots. No specimen is sufficiently perfect to show the shape 

 or the length, but the shape appears to be similar to that of M. hydropica, 

 and the insect much smaller than it, for the breadth is 4.5 mm , and the length 

 of one segment, '2""". 



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

 Denton). 



MUSCA spp. 

 PI. 5, Figs. 80, 81, 99, 100. 



A wholly different form of larva is represented in PI. 5, Figs. 80, (SI, 

 and on one of the stones are found the mouth parts of another, PI. 5, Figs. 

 'JD, 100, which are quite different from those of Musca ascarides. 



Chagrin Valley, White River, Colorado (W. Denton). 



Family TACHINID^: Loew. 



TACHINA Meigen. 



TACHINA sp. 



Tachina up. Scudd., Bull. U. S. Geol. Geogr. Surv. Terr., IV, 756 (1878). 



To this genus is referred provisionally a small but stout and densely 

 hairy fly, with thick, slightly tapering abdomen, broadly rounded at the tip, 



