March, 1917.] CoLE : OSTEN SaCKEn's GrOUP " PcECILANTHRAX." 75 



Moodie)," has the brown of the wings very pale. This may be an 

 immature specimen. AH the abdominal segments except the first have 

 short white tomentum mixed with the usual yellow tomentum. In 

 most specimens the tarsi are dark. This species does not have the 

 base of the front femora dark as in alpha. Some specimens have the 

 lateral margins of all segments except the first reddish. 

 Anthrax poecilogaster O. S. (fig. 12). 



Anthra.v pa:cilogaster O. S., Biologia, Dipt., i, 118. 



" Head yellowish, almost wax-color, with appressed golden pubescence, 

 and black, erect hairs ; vertex black, the upper part of the occiput grayish, 

 beset with pale orichalceous appressed hairs ; basal joints of antennae reddish, 

 third joint black. Thorax grayish-brown, with an appressed fulvous pubes- 

 cence forming a pair of indistinct stripes in the middle, and longer, erect 

 fulvous hairs in front and on the sides (when the pubescence of the dorsum 

 is not abraded and the surface not greasy, two dark stripes are visible on the 

 grayish-brown background). The scutellum reddish, black at the base. First 

 segment of abdomen black, the others rufous, with a transverse black spot in 

 the middle of each, beginning with the second (these spots visible in abraded 

 specimens only). The hairy covering of the abdomen consists of a partly 

 rufous, partly yellowish white tomentum, the latter predominating on the sides 

 and on the anterior part of the second segment. In well-preserved specimens, 

 in the middle of each of the segments 2, 3, and 4, there is a short, tuftlike 

 crossband of black hairs, broadly interrupted in the middle, the interruption 

 being filled with a whitish tomentum ; tufts of black hairs along the abdomen, 

 beginning with the second segment; legs rufous, the tips of the tarsi darker. 

 Knob of the halteres whitish. Wings on the pattern of halcyon, but nar- 

 rower; a stump of a vein within the third posterior cell; a hyaline spot close 

 by the axillary incision across the middle of the axillary cell, sometimes reach- 

 ing the anal cell also ; the ends of the second and upper branch of the third 

 vein thickly clouded with brown ; the hyaline space in the discal cell rather 

 large and in contact with the fotirth vein ; the hyaline space connecting this 

 spot with the posterior margin rather clear, the intercalary spot at the distal 

 end of the second basal cell very distinct ; the brown color not very dark and 

 variegated with yellowish rufous. Length 11 to 12 mm. 



"Habitat. — North America, Cal., Mexico, N. Sonora, Tehuacan. 

 Seven specimens. 



" Parcilogastcr differs from arcthusa as follows: (i) Third pos- 

 terior cell is not bisected, but contains a stump of a vein; (2) the 

 black tufts on the sides of the abdomen are very distinct on the 

 second, as well as on the following segments; (3) the hyaline spot 

 in the distal half of the second basal cell near the proximal end of 

 the discal cell is not obsolete, but very distinct; (4) there is a more 



