100 DIPTERA OP NORTH AMERICA. [PART III. 



Myrmecomyia is not only very like Cephalia in appearance, 

 but closely allied to it in reality. However, they may be distin- 

 guished by the presence, in Cephalia, of a mesothoracic bristle, 

 and by the absence of the coarctation of the first abdominal 

 segment, peculiar to Myrmecomyia. The alulae and tegulae in 

 Cephalia, although small, are not wanting ; the posterior angle 

 of the wing, although very shallow, is likewise apparent. 



HI. myrmecoides LOEW. $ .(Tab. VIII, f. 9.) Nigra, alarum 



hyalinarum ima basi et apiue extreme uigris. 

 Black ; wings hyaline, extreme root and apex black. Long. corp. 0.25 



0.27; long. al. 0.21. 

 SYN. Cephalia myrmecoides LOEW, Wien. Ent. Monatschr. IV, p. 83. 



Black, glossy. Head shining black, face and cheeks usually 

 brown. The very broad and long front, descending in a steep 

 slope, has a very narrow middle stripe of velvet black, which 

 does not reach much beyond the middle of the front, but is con- 

 nected by a furrow with the frontal fissure ; the latter is not in 

 the shape of an arc, but of an angle. Ocelli approximated to 

 each other. The vertex bears two strong bristles, and on both 

 sides of them two shorter ones; moreover, far back of the ocelli 

 there are two small erect bristlets, while there are none in the 

 immediate vicinity of the ocelli. The conspicuously large lateral 

 parts of the front have irregular, wrinkle-like, transverse impres- 

 sions, and along the orbits a very narrow border of white pollen. 

 Antennae long and narrow, reaching to the anterior edge of the 

 mouth; the first two joints brownish-red, the third black; arista 

 with a very short pubescence. Face convex, descending obliquely 

 in profile, but not excavated; the anterior edge of the mouth 

 not drawn upwards ; antenna! foveae indistinct ; the very narrow 

 lateral parts of the face with a thin white pollen. Eyes higher 

 than broad. Cheeks rather broad. Clypeus projecting over 

 the anterior edge of the mouth, however its longitudinal diameter 

 does not equal its moderate transverse diameter ; the rather 

 broad palpi blackish-brown. Thorax rather long and narrow, 

 broader in the region of the wings than before and behind. 

 Scutellum very small, convex, with two bristles. The metathorax 

 descends in an inclined plane, and is conspicuously long; the 

 pectus rises obliquely from the middle coxce towards the front 



