HOUGH: SOUTH AMERICAN MUSCID.E. 227 



sides ventrad the ocelli are two more pairs of transfrontal bristles. 

 The bristles of the vertex are as follows : The great ocellars, 

 small and parallel, as is usual in this genus ; one large lesser 

 ocellar pair, as large as any of the bristles of the vertex (a very 

 unusual feature) ; one hardly visible lesser ocellar pair; the 

 postverticals are not present ; the inner and outer verticals and 

 the occipito-central bristles are present and are small, as is usual 

 in this genus. 



The head of the female is 2.2 mm. wide. The width of the 

 front is 0.6 mm. The sides of the front are almost exactly 

 parallel throughout. The frontal vitta is between four and six 

 times as wide as one geno-vertical plate. There are about five 

 transfrontal bristles, two ascending frontals, and a good-sized 

 pair of preocellars. There is notliing unusual about the bristles 

 of the vertex ; all are present, and of normal size and direction. 

 There are no orbital bristles. 



The length of the second joint of the antenna? is 0.25 mm. ; of 

 the third joint, 0.55 mm. The arista is thickly and long plu- 

 mose, and the base of its rachis is yellow. 



The cha'totaxy of the thorax is shown in figure 14. The 

 ground color of the thorax of the male is a pale 3^ellowish 

 brown, and it has everywhere a thin, yellowish pollinose coat- 

 ing. If looked at vertically there are faint suggestions of 

 stripes in the dorso-central and acrostical lines. This yellow- 

 brown ground color appears in the female only on the humeri 

 and prothorax, on the base and tip of the scutellum, along the 

 sutures bounding tlie meso-pleura and sterno-pleura, on the 

 ptero-pleura, on the postalar callosity, and on the mesonotum, 

 near the scutellum. The most of the thorax of the female has 

 a black ground color and is covered with brownish or gray 

 pollen, which forms three broad but rather indistinct stripes — 

 a median and two lateral. 1 have observed that, when a species 

 has two ground colors, as in this female, their relative extent 

 is very variable in different specimens. 



The abdomen of the male. — First segment : Pale brownish 

 yellow with a dark brown transverse fascia on each cephalo- 

 lateral angle ; a marginal row of small appressed macrochsetj©, 

 which are larger towards the sides of the segment. Second 

 segment : Most of the cephalic half and also a narrow median 

 stripe are pale brownish yellow ; the caudal half and two pro- 



