308 Annals Entomological Society of America  [Vol. XIV, 
the sternum apart, slightly oblique, posterior spiracles situated on the 
accessory pieces. Sternum lanceolate, attaining the length of the seg- 
ment, expanding before tapering to the cephalic margin; marginals 
approximating, distributed for a short distance along the lateral borders; 
conjunctiva spinulose. 
Segment VII. Tergum similar in structure and character to seg- 
ment VI, a more noticeable thinning of the chitin dorsad. Sternum with 
rounded caudal margin; the marginals arranged in a semi-circle around 
the border; conjunctiva smooth. ; 
Segment VIII. Tergum similar in structure to @mene, composed of 
two lateral plates whose caudal extremities flare and adhere to the mar- 
gin, cephalad the plates slightly approximate, tapering toward the 
cephalic margin; discal area hyaline, spaceous; marginals diverse, 
regular. Sternum composed of two broadly ovoid sclerites tapering to a 
point caudad, attaining one-half the length of the segment; sete dis- 
tributed over the entire surface, bristlelike; conjunctiva smooth. 
Segment IX. Suranal plate scoopshaped; setze barely the width of 
the club apart; setulae few, strong; subanal plate spade-shaped; sete 
regular; setulae around the margin spinelike, remainder shorter; cerci 
conical to subcylindrical, clothed with fine long setulz, apicals long 
and fine; sense organs consist of two large membranous discs from 
which emerge fine hairlike papille and two small tubercles, the former 
cause the apices of the clubs to appear chipped or notched. 
Hylemyia flavipennis Fallen.* 
The structure and character of the segments and intersegments are 
very similar to those of coarctata. In flavipennis the length of the 
segments and intersegments is equal to their breadth; the accessory 
pieces are absent, and the shape of the ventral sclerites vary slightly 
from that of coarctata. In flavipennis the caudal border of the sternum 
of the sixth segment is truncate with the marginals arranged along the 
caudal margin whereas in coarctata the caudal extremity tapers to a 
point with the marginals arranged laterad. The conjunctiva of the 
sixth segment in flavipennis is spinulose on the caudal third and smooth 
for the remaining area whereas in coarctata the whole surface is spin- 
ulose. The sternum of the seventh segment of flavipennis tapers ceph- 
alad, in coarctata the cephalic half of the sclerite expands before reach- 
ing the margin. Further in flavipennis the sete of the suranal plate lie 
closer to each other. 
Hylemyia juvenilis Stein. 
Segments one and two slightly longer than the foregoing interseg- 
ments, segment VIII equal to intersegment three; suranal, subanal 
plates and cerci densely pubescent. Intersegments spinulose except 
the fourth which is smooth throughout. 
Segment VI. Tergum glabrous, completely chitinized, shieldlike, 
encasing the tergal region; accessory pieces absent; marginals diverse, 
regular, continuing for a short distance along the ventral border; spir- 
acles barely the width of the sternum apart, oblique, posterior spiracles 
