DIPTERA SCIOMYZID.E. 545 



the posterior, large, transverse vein, and its approach to the posterior 

 margin, tin- bristly nature of the legs, ami the length and comparative slen- 

 derness of the tarsi all, excepting parts of the neuration, characters open 

 to little question render this fly peculiar and its exact location somewhat 

 dubious. When, however, the neuration of the wing is sufficiently well 

 known to enable us to understand more definitely the character of the basal 

 cells and other parts of the base of the wing, the relation of the auxiliary to 

 tin- first longitudinal vein, and to map unquestionably the whole course of 

 the fourth longitudinal vein, we shall probably be able to arrive at verv 

 precise conclusions. 



In addition to the features above mentioned, it may be added that the 

 thorax is subipiadrate, scarcely longer than broad, furnished with distant, 

 long, curving bristle.-, disposed in rows, but in no individual well enough 

 preserved to give further details of distribution. The abdomen is composed 

 of five visible, subequal joints; its mass compact, scarcely constricted at 

 the base, regularlv and pretty strongly arched on a side view, tapering 

 rapidly on the apical half to a bluntly rounded apex, the surface abun- 

 dantly clothed with rather delicate spinous hairs, those at the posterior edge 

 of the segments longer, and forming a regular transverse row. The meta- 

 tarsus of the middle leg is proportionally longer than in the others, where 

 it is about half as long as the other joints combined 



Measurement of average individuals: Length of body as curved. 

 4.25"""; of head, O.G5 mm ; of thorax, 1.7"""; of abdomen, 2.2""": breadth of 

 bead, ().85 mm ; of thorax, 1.25"" 11 ; of abdomen, 1.4 mm ; length of flagdlum 

 of antennas 0.16"""; of style, 0.1!)"""; of wing, 3.4""".': breadth of same. 



1.2 ; length of femora, 0.75"""; of tibia-, O.!)5 mm ; of fore tarsi, 0.8;")"""; 



of middle tarsi. 1.5""": of hind tarsi, l.j mi "; of fore metatarsi, 0.4""": of 

 middle metatarsi, il.til"""; uf hind metatarsi, 0.48"""; breadth of femora, 



0.28 ; of tibiae, 0.12"""; of metatarsus, 0.08 mui ; of tip of tarsi, 0.05"""; 



length of claws, 0.0!) 



Green River. Wvoming. Numerous specimens, collected bv Mr. !".('. 

 A Richardson, Dr. A S. Packard, Prof. L A. Lee, Messrs. F. C. Howditch, 

 and S. ll.Sci>ddcr. Station lii on the White River in western Colorado (Dr. 



C. A. White 



VOL XIII .'!' 



