494 PROCEEDINGS OF THE ACADEMY OF [Sept., 



a very conspicuous curved hook; eighth sternite with two strong 

 decurved bristles on the caudal margin. 



ilfoie.— Length, 16 mm.; wing, 17.2 mm. 



Frontal prolongation of the head rather elongate, shining, dull 

 yellow; palpi dull yellow, the two terminal segments brown. An- 

 tennae short, the three basal segments yellow, remainder of the organ 

 with the basal swelling of each segment brownish black, the remainder 

 5'ellow, the two terminal segments a little darker. Head brownish 

 yellow, an indistinct brown median line extending the length of the 

 head. 



Thoracic dorsum dull light yellow, unstriped or nearly so, the 

 usual interspaces on the praescutum being a little more grayish 

 only. Pleura yellow, sparsely whitish pollinose. Halteres rather 

 long, slender, pale, the knobs darker. Legs with the coxae and tro- 

 chanters dull j^ellow, the remainder broken. Wings grayish yellow, 

 the costal region and the stigma brighter yellow; an interrupted 

 vitreous band before the stigma, broadest in cell 1st Ri before the 

 stigma and in cell 1st M2, narrowly connecting the two along the 

 cord; a small, indistinct, vitreous spot beyond the stigma. Venation 

 as in Plate X\T, fig. 15. 



Abdomen dull brownish yellow. Male genitalia (see Plate XVIII, 

 fig. 36) with the eighth tergite prominent, its caudal margin straight 

 across. Ninth tergite (see Plate XIX, fig. 53) very long, subquad- 

 rate, the caudal margin with a deep acute notch, the lateral lobes 

 produced into long, somewhat curved horns which are directed 

 slightly inward, the extreme tip ventrad. Ninth pleurite (see Plate 

 XX, fig. 64) complete, rather small, the dorsal end sharply angular 

 and barely attaining the ninth tergite; appendages two: a short, 

 caudal-lying fleshy lobe with abundant long hairs (a), underneath 

 the lobe is a large, powerful, chitinized hook directed dorsad and the 

 tip outward, decussate wdth its mate of the opposite side; a flattened 

 appendage lying more cephalad, its anterior face chitinized and 

 notched; in a position of rest, the appendage lies beneath the extensive 

 ninth tergite. Ninth sternite extensive, deeply notched beneath, 

 bearing a fleshy, elongate-oval lobe which hangs subpendulously in 

 the notch, but is attached to the sternite by one broad face. Eighth 

 sternite (see Plate XVII, fig. 27) with the caudal margin broadly 

 concave, at each end of this notch a single very large bristle, decussate 

 with its mate of the opposite side. Penis-guard and the gonapophyses 

 rather small, directed caudad, viewed from beneath (see Plate XXI, 

 fig. 80) shaped somewhat like a trident. 



