HOUGH: SOUTH AMERICAN MUSCID.E. 211 



The front of the male is linear in the middle, expanding both 

 dorsad and ventrad. Ventrad the linear part the geno-vertical 

 plates are whitish pollinose and bear about four ])airs of trans- 

 frontal bristles. Dorsad the linear part are about three pairs 

 of transfrontals. All these bristles are very small. The great 

 ©cellar bristles are hardly distinguishable by size from the 

 lesser, and the whole ocellar group, including the postvertical, 

 are very small. The inner vertical is of good size, the outer 

 vertical small, the occipito-central present. The cilia of the 

 posterior orbit are very small. 



The front of the female is about one-third as wide as the head, 

 and broadens slightly from the antenna^ towards the vertex. 

 The geno-vertical plate is polished except on the lateral half 

 or less of the ventral third, which is yellow pollinose. There 

 are about eight transfrontals. Laterad the ocelli are a couple 

 of pairs of bristles of small size, which i)oint laterad. The bris- 

 tles of the ocellar group are small, but the great ocellar pair is 

 much larger than in the male. The inner and outer verticals 

 are of fair size and about equal ; the occii)ito-central is present. 

 The cilia of the posterior orbit are longer than in the female. 



The thorax looks as if finely punctate, and bears remarakbly 

 few bristles, as is shown in figure 1. The variations are: (1) 

 Usually only one humeral, but sometimes a second, much 

 smaller; (2) the presutural is sometimes absent; (3) the sec- 

 ond dorso-central is only sometimes present ; it is smaller than 

 the other ; '4) the smaller of the two sterno-pleurals may be ab- 

 sent. It is, of course, possible that the variations mentioned 

 may be due to injuries received by the specimens, but that is 

 not my opinion. Not a single specimen has an anterior sterno- 

 pleural bristle. 



The only noteworthy bristles of the legs are as follows : 

 Middle tibia, posterior surface near flexor border, one at junc- 

 tion of basal middle and a second at that of middle and apical 

 thirds ; hind tibia, lateral surface has three small flexors and 

 one or two extensors, mesal surface has one or two extensors. 



The wing is shown in figure 2. 



I have very little doubt that Pyrellia suspicax Walk., Mexico, 

 is the same as MorelUa hipunda Fabr. Van der Wulp thought 

 that Pyrellia iris Bigot was the same as P. suspicax Walk. I am 

 not prepared to affirm or deny this. 



