26 



HOUGH. 



[VOL. I. 



from the Rocky Mountains (the source of Bigot's specimen) 

 are in my collection. 



FIG. 8. 



MUSCINAE MUSCAEFORMES. 



Middle tibia with a prominent macrochaeta on its flexor surface . 2 

 (The male of some European Mesembrinae has no such macrochaeta, 

 but its middle tibiae are elongate and on their flexor surface thickly 

 hairy.) 



Middle tibiae without such a prominent macrochaeta . . 3 



Sternopleural macrochaetae 1:2; elbow of fourth vein forming a rounded 

 angle ; no orbital macrochaetae, but the geno-vertical plate uniformly 

 beset with minute bristly hairs ; transf rental macrochaetae small and 

 weak, often difficult to see . . . Pseudopyrellia Girschner. 



Sternopleural macrochaetae 1:3; 

 first longitudinal vein ending in 

 the costa at about the middle of 

 the wing ; small cross-vein about 

 opposite the end of the first longi- 

 tudinal ; elbow of fourth longi- 

 tudinal not forming an angle but 

 a gentle curve convex toward the 

 hind border of the wing forming 

 an apical cross-vein which is longer than the terminal portion of the 

 fourth vein before its curvature . . . Pyrellia Desvoidy 

 Sternopleural macrochaetae varying, i : 3, i : 2, o : i ; if (rarely) i : i 

 then the anterior notably the smaller ; first longitudinal vein ending in 

 the costa far beyond the middle of the wing; small cross-vein a long 

 distance basad to the end of the first longitudinal ; fourth longitudinal 

 sweeping in a broad curve, convex toward hind border of wing, towards 

 the third, thus forming an apical cross-vein, which, however, in our spe- 

 cies, is not longer than the terminal portion of the fourth vein before 

 its curvature ...... Mescmbrina Macquart 



Bend of fourth longitudinal forming a rounded angle. Outline of arista 

 as a whole fan-shaped. Sternopleural macrochaetae I : 2. 



Musca Linnaeus 



Bend of fourth longitudinal not forming an angle at all, but a gentle 

 curve ............ 4 



Antennae separated at their base by a distinct ridge ; Sternopleural mac- 

 rochaetae 0:2; eyes very distinctly hairy Graphomyia Desvoidy 

 Antennae not thus separated ; Sternopleural macrochaetae 1:2; eyes 

 not distinctly hairy . . . . . . . . 5 



Arista naked . . . Synthesiomyia Brauer and Bergenstamm 

 Arista plumose Morellia Desvoidy 



