PAPERS ON ZOOLOGY 315 



fewer hairs; the area on the first abdominal segment is 

 much smaller than those on the succeeding segments and 

 not raised into a welt ; the area on the eighth abdominal 

 segment is less conspicuous than those of the preceding 

 seven segments which are raised into broad oval welts. 

 The areas on the dorsal surface of the segments are 

 much narrower and not raised into welts ; they occur as a 

 narrow, parallel-sided band on the anterior margin of 

 the metathorax and on abdominal segments two to eight, 

 occupying a position nearly opposite the welts on the 

 sternum but with no connection across the pleural region 

 except the areas on the metathorax and the eighth ab- 

 dominal segment where the bands completely encircle 

 the body although less developed on the pleural regions. 

 The body setae are very small and scattered, a widely 

 separated pair a short distance caudad of the ventral 

 abdominal welts, on the thoracic segments occupying 

 corresponding positions but with two setae to a puncture. 

 The dorsal setae are very small and widely separated, 

 situated nearly midlength between the welts. 



The spiracular disk is very similar to that found in the 

 genus Dicranomyia, the spiracles being very large, elon- 

 gate-oval, placed obliquely on the sides of a deep split 

 and so capable of close approximation. The usual ven- 

 tral lobes of the disk are represented by two contiguous, 

 roughly circular, dusky areas, (fig. 7) each with three or 

 four tiny setae near the middle of its caudal margin. 

 Anal gills (fig. 6) four in number, distinct, each gill 

 rather short, simple, tapering gradually to the blunt tip. 



The head-capsule is of the simple, generalized struc- 

 ture of this tribe, with flattened, mussel-like constituent 

 plates. Labrum (fig. 1) transverse oval, the margin pro- 

 vided with short yellow hairs, a larger tuft on either side. 

 On the disk are two oval subhyaline areas, each of which 

 are provided vdih. three sensory papillae; at either end 

 of the labral sclerite a roughly conical chitinized sup- 

 porting structure. Mentum (fig. 5) broad, the anterior 

 margin gently convex and provided with 11 teeth, the 

 median tooth largest, the others gradually decreasing in 

 size to the outermost which is very small and indistinct ; 



