1898.] NATURAL SCIENCES OF PHILADELPHIA. 179 



Head. — The antennse, bucca?, genae, vibrissa! ridges, facial fossa 

 and ventral third to half of the geno-vertical plate are all pale 

 yellowish -brown. The remainder of the geno-vertical plate is bluish 

 gray. The frontal vitta is brown with a slight reddish tinge. The 

 posterior orbit differs in the two sexes. In the female it is about 

 0.1 mm. wide, bluish-gray dorsally and shading off ventrally to pale 

 yellow ; in the male it is narrower, entirely absent along the dorsal 

 third or half of the eye and entirely yellow. In the female the front 

 occupies about one-third of the width of the head and is mostly made 

 up of the frontal vitta the geno-vertical plate being very narrow. 



Bristles of the head. — Female : — Seven to nine transfrontal of good 

 size and a few small intercalarv, sometimes the larger ones decussate 

 and sometimes not, they extend a little ventrad the insertion of the 

 antennas. Ascending frontal, one. Orbital as mentioned in the 

 generic description. Greater ocellar, of good size, divergent. Lesser 

 ocellar, several pairs all parallel to the greater; one very small pair 

 is situated ventrad the greater, there are several small pairs dorsad 

 the greater and one pair at the dorsal border of the ocellar triangle 

 is half to three quarters the size of the greater. Inner vertical and 

 outer vertical, inserted as usual, equal ; only a little larger than the 

 ascending frontal, larger than the greater ocellar. Post vertical 

 small, erect, parallel to one another, inserted on the occipito-vertical 

 border a trifle caudad the line of the inner verticals. Occipito- 

 central, very small and delicate, inserted very close to the occipito- 

 vertical edge. Occipito-lateral not present. Cilia? of posterior 

 orbit rather sparse but well aligned, extending ventrad to the caudo- 

 ventral angle of the eye. Bucca: vertical diameter as seen from in 

 front nearly one half that of eye ; along edge of mouth-opening a 

 series of large stout bristles, the remainder sparsely beset with min- 

 ute hairs. Vibrissal ridges: a few minute bristles dorsad the prin- 

 cipal vibrissa extending to a point a very little dorsad the ventral 

 end of the arm of the frontal suture. 



Male: — Transfrontal, as mentioned in the generic description, 

 about seven in number. Inner vertical good sized. Outer vertical 

 absent as is usual in male Muscida?. Greater ocellar much smaller 

 than in the female (the usual thing in Muscida?). Lesser ocellar, 

 quite numerous, some of them almost equal to the greater. Post 

 vertical as in the female. Occipito-central (doubled in one speci- 

 men), cilia? of posterior orbit, bucca and vibrissal ridges as in female. 



Antenna. — Third joint about twice as long as the second. Arista 



