242 ERNEST A. BACK. 



only a little broader, terminating in two lateral lobes, or pro- 

 cesses, which extend as far as the insertion of the second 

 segment of the style; fourth segment, or first segment of the 

 style, somewhat "Y" shaped, the terminal lobes being rather 

 more than one-half the entire length of the segment, longer and 

 more slender than those of the third segment; fifth segment, 

 or second segment of the style, longer than the entire length 

 of the preceding, narrowed, almost pedicellate at base, flat- 

 tened beyond the tip of the lobes of the preceding segment, 

 and then obtusely pointed, somewhat irregular in shape and 

 shallowly sulate, clothed with very fine short pile. 



Thorax convex, nearly bare, wholly without macrochsetae 

 except a very few short intra-alar ones. Legs rather stout, 

 without macrochaetae except a few short ones at the tip. 

 Wings as in Ceraturgus cruciatus, but broader, marginal and 

 first posterior cells open; the posterior intercalary vein arises 

 from the posterior basal transverse vein a short distance from 

 the base of the discal cell. In melas, the type, and rufus, the 

 fourth posterior cell is broadly open, in lobicornis it is open, 

 closed or petiolate. Anterior cross-vein near middle of the 

 discal cell. 



Abdomen in structure rather like that of Dioctria, shorter 

 than the wings, the sides nearly parallel, or gently concave, 

 to the tip of the fifth segment in the male, in the female the 

 fifth segment gently narrowed behind; a little narrower than 

 the thorax in the male, in the female about as wide; flattened, 

 so that transversely it is only convex above, gently grooved 

 at the incisures, each segment being gently convex longitud- 

 inally; smooth, nearly bare, except sparse very short pile; 

 segments of nearly equal length, the sixth a little shorter, the 

 seventh very short. Hypopygium small. 



This description is drawn from a male of melas, and a female 

 of rufus, which agree closely in structure. In lobicornis the 

 antennal protuberance is more obtuse, and the face more 

 flattened, in profile very narrow, and the prominence near the 

 middle wholly wanting. The fourth posterior cell variable, 

 and the first posterior cell strongly coarctate. From the 

 diagnosis of this genus given by Monsieur Bigot, there are 



