20 ENTOMOLOGICAL NEWS [Jan., '15 



32 Hind tibiae bearing a single bristle. (Mex.) longiseta Coq. 



Hind tibiae with scattered bristles. (Mex.) depressus Aid. 



33 Hypopygium and its appendages very small, the latter finger-like. 



(Mex.) siinilis Aid. 



Hypopygium and its appendages large 34 



34 Hypopygial lamellae large, flat, with an excavation at tip and short, 



curling, dark hair on the inner surfaces. (Mex.) 



atrolamellatus Aid. 



Lamellae broad, nude, each composed of two flattened plates, the 

 outer attached to the inner near the base. (Mex.) ..clunalis Coq. 



35 Face with abundant slender hairs 36 



Face bare 41 



36 Face with dark hairs. (Mex.) barbatus Aid. 



Face with pale hairs 37 



37 Middle metatarsi with a row of crooked bristles below 38 



Middle metatarsi normal 39 



38 Tip of abdomen with a tuft of long hairs, the longest being nearly 



as long as the last four segments of the abdomen. (U. S.,- W. I., 



Mex., S. Am.) caudatus W'ied. 



Longest hairs at the tip of the abdomen not much longer than the 

 last segment. (U. S.) scobinator Loew 



39 Middle tibiae with a strikingly long apical spur. (U. S.) 



calcaratus Loew 

 Spur of middle tibiae rather short 40 



40 Last four joints of fore tarsi of regularly decreasing length. 



(U. S.) inermis Loew 



Last four joints of fore tarsi short, second and third subequal, 

 fourth as long as the two preceding. (U. S.) . . .patibulatus Say 



41 Arista at least two-thirds as long as the entire body 42 



Arista much shorter 45 



42 Fore metatarsi with long cilia above 44 



Fore metatarsi without long cilia 43 



43 Arista ending in a small disk. (Mex.) nobilissiinns Aid. 



Arista plain. (Calif.) occidcntalis Bigot 



44 Hypopygial appendages pale, middle metatarsi ciliated. (U. S.) 



comatus Loew 



Hypopygial appendages blackish, middle metatarsi plain. (U. S.) 



crinitus Aid. 



45 Thoracic dorsum covered with thin white pollen, front densely 



silvery pollinose 46 



Thorax and front mostly shining 47 



46 Legs wholly black, fore tibiae with three or four bristles in a row. 



(Mex.) argentatus Aid. 



Fore and middle femora and base of fore tarsi yellow, fore and 

 middle tibiae each with two long bristles. (Fla.) .pruinosus Coq. 



