238 DIPTERA OF NORTH AMERICA. [PART IV. 



Section V. ANISOMERINA. 



Two submarginal cells (only one in CladoUpes) ; three, four, or five posterior 

 cells ; discal cell closed or open ; subcostal cross-vein near the tip of the 

 auxiliary vein, posterior to the origin of the second vein. Eyes glabrous. 

 The normal number of the antennal joints is six in the male and not more than 

 ten in the female. Tibiffi with spurs at the tip ; etnpodia distinct ; ungues 

 generally smooth. 



This section is easily distinguished by the aberrant number of 

 antennal joints. In other respects, the most numerous genus of 

 the family, Eriocera is exceedingly lilve the L'imnophilina in its 

 venation and the structure of its male forceps. The species of 

 Eriocera and Fenthoptera, have either five or four posterior 

 cells, a character which, in this section, seems to have no higher 

 importance than for the distinction of species. In Anisomera 

 and CladoUpes the posterior cells are reduced to the unusual 

 number of three ; to which, in the latter genus, is added the dis- 

 appearance of the first submarginal cell. 



These differences in the venation notwithstanding, strong links 

 of affinity unite these genera. The male has six-jointed antenna?, 

 which, in some species, are much longer than those of the female, 

 sometimes more than twice the length of the body; while in other- 

 wise closely allied species the antennae of both sexes are short 

 and nearly of the same length. These modifications in the rela- 

 tive length of the antennae occur in the three principal genera of 

 this section, Anisomera, Fenthoptera, and Eriocera. The female 

 antennae are short, and the structure of their apical portion is 

 such as to leave the number of the joints, composing it, some- 

 what uncertain, especially in dry specimens. On living female 

 specimens of Eriocera and Fenthoptera I have distinctly counted 

 ten joints. 



The ovipositor of Anisomera has a peculiar structure ; the 

 valves are short and blunt, the upper ones much shorter than the 



