AMERICAN DIPTERA. 83 



]?I»ccll4»cerus Mik. ^ o^ 



Mik. nii)teroIoKisc.he Untersucluiiij;eii, p. 3, 1878. 

 MA LES. 



1. Antcnnal arista with a lamella in the luidflle as well as at th( tip. 



I>iii4»(laf iiM Loew. 

 Antcnnal arista with an apical lamella only 2. 



2. Anterior femora thickened, hlack below on the basal half- . -olyiiipitv n. sp. 

 Anterior femora not thickened, yellow 3. 



3. Outer side of fore femora with long, curly hair aural U!« n. sp. 



Outer side of fore femora with plain hair 4. 



4. Anterior tibiie with a row of erect, flattened bristles on the outside below. 



KilllllN O. $. 

 Anterior tibije witli only a few common bristles on this part- ■ino'chuM Loew. 



FEMALES. 



1. Hind femora yellow, two preapical bristles aiiratus. 



Hind femora largely black, one prea])ical bristle 2. 



2. P^ront tilwai wholly yellow nioecliiim. 



Front tibiip largely black 3. 



3. Four anterior femora green-black, the apical third yellow, distinctly limited. 



NaiitiM. 

 Four anterior femora largely yellow, the brown at base not distinctly limited. 



olyiiipitc. 

 (The f'oniale of hiiKxhdiix is iiii known) 



jflacellocerus olyiapisi' n. sp. 



Mule. — Face long, bright yellow, slender in tlie middle ; antennae yellow, the 

 third joint blackened except at base, second joint rudimentiiry ; arista one and a 

 third times as long as the vertical diameter of the head, white except the incras- 

 sated base and the obovate black lamella, which is a little smaller than the third 

 joint; lateral and inferior orbital cilia light yellow. Thorax and abdomen 

 bronze-green ; tegulae yellow, with black cilia; fore coxse yellow, bare except the 

 tip. Fore femora incra.ssated at the base, with a peculiar circular black spot seem- 

 ingly stamped upon the outer side, reaching beyond the middle; tlie inner side 

 is yellow, with a delicate pruinosity ; fore tibise yellow, with nnmcrous and rather 

 long bristles ; fore ta,i"si a little compre.s.sed. shoit, black ; posterior femora and 

 tibiai yellow, tii)s of the latter narrowly blackened, tarsi black ; bristles of the 

 tibiaj rather long. Hypopygium large, basal part shining black, central segment 

 bronze-green behind, lamella; whitish, covered with black hairs, those of the 

 margin hardly coarser. Wings exceedingly slender, grayish, lighter at the root. 



Female. — All the body color darker, face wider and greenish yellow, third joint 

 of the antenna' l)lack, all the coxa; black, femora more or less dark on the basal 

 part, the hind ones wholly black-green except the apical third ; tibise black on 

 the apical third or fourth. Wings longer and much wider than in the male. 

 Length (i mm. ; of wing 4.2 ram. 



Two males, two tenuiles, Olyinpia, Wasli. (Trevor Kiiicaid), June 

 8 and July 1. 



iVaoellocerns aiiratus n. sp. 



Male. — Face long, golden-yellow, very narrow in the middle, antennae bright 

 yellow, small, the second and third joiiits both very minute and rudimentary, 

 arista black, one and a half times the length of vertical diameter of the eye, the 



TRANS. AM. KNT. SOC, XXIII. MARCH, 1896. 



