ORTALID^E — MYRMECOMYIA. 99 



baud for comparison, and was obliged to write from memory. 

 The bristles on the first abdominal segment, the distance inter- 

 vening between the anterior ocellus and the posterior ones, and 

 even the shape of the ovipositor remind very much of some 

 genera in the group of Richardina, from which, however, Mis- 

 chogaster is easily distinguished by the distinct bristles on the 

 first longitudinal vein and the unarmed femora. 



The typical species of the genus is the Cephalia femoralis 

 Wied. No species from North America are as yet known. 



Gen. VI. MYRMECOMYIA R. Desv. 



Charact. — Body slender, not unlike that of an ant. 



Head comparatively large ; occiput conspicuously stout behind the 



vertex. 



Front of a uniform, considerable breadth, very long and steep, so that 



the antennae are below the middle of the head ; the very large 



lateral stripes of the front have wrinkle-shaped cross impressions. 



Antenna reaching a little below the anterior edge of the mouth ; 



arista with a rather short pubescence. 

 Front convex, not excavated in profile, but descending in an in- 

 clined plane ; clypeus of a moderate transverse diameter ; cheeks 

 rather broad. 

 Thorax somewhat narrowed anteriorly ; scutellum small, with two 



bristles. 

 Abdomen very much attenuated at the basis ; the narrow first seg- 

 ment without bristles ; about its middle it is so coarctate that its 

 anterior portion assumes the shape of a knot. 

 Feet very slender. 



Tegulce wanting; wings narrow, running into a point towards the 

 basis, so that the posterior angle of the wing and the alula are 

 wanting ; auxiliary and first longitudinal veins closely approxi- 

 mated ; the two posterior basal cells small ; the posterior angle of 

 the anal cell rather sharp. 

 The very peculiar structure of the head, the approximated 

 ocelli, the absence of bristles on the first abdominal segment and 

 its peculiar coarctation, sufficiently distinguish this genus from 

 Mischogaster. The species upon which it was founded by R. 

 Desvoidy are unfortunately unknown to me, so that I cannot 

 affirm with certainty whether the characters as based by me 

 upon the species described below would in all particulars apply 

 to them. Judging by his statements, however, it seems very 

 probable that the discrepancies are not important. 



