34 S. W. WILLISTON, M. D. 



recedinf to the oral murgin, resembling in structure the species of Para- 

 yws, but more concave above the tubercle and more receding below it; 

 the tubercle being higher up. Cheeks narrow. First and second joints 

 of the antennae extremely short, so that the third joint appears sessile, 

 the latter large, subquadrate, as broad as long, the angles rounded, and 

 narrower on the basal portion ; arista small, bare, very short, not as long 

 as the third antennal joint, remote from the base, situated upon the 

 anterior rounded angle near the end of joint. Scutellum small, convex, 

 but thinned along its margin. Abdomen very convex above, beyond 

 the middle being in cross-section two-thirds of a circle ; first segment 

 short ; second segment moderately long ; third segment much shorter 

 than the second, in the middle on the sides nearly as long, the in- 

 cisure in front forming a deep stricture, less evident behind; fourth 

 segment very large, as long as the three preceding together, forming half 

 of an ellipsoid, flattened on one side, the strongly convex end extending 

 beyond the anal opening, and wholly concealing the following segments. 

 The sides of the abdomen are directed downward and inward inclosing 

 toward the outer part of the venter a deep cavity, shallower on the 

 second and third segments ; at the posterior part of this cavity, and con- 

 cealed by the posterior rim, is the anal opening looking obliquely forward; 

 back of the anus on the rim on each side is a small obtuse membranous 

 flap or process. Legs as in Paragvs — rather short and moderately 

 strong, the posterior metatarsi thickened. Wings more like those of 

 Sijritta than of Pdragus. The first longitudinal vein joins the costa 

 a little before the tip of second vein, and then by a curve at the tip, so 

 that the vein runs parallel to the costa for some distance. The anterior 

 cross-vein is near the basal third of discal cell, and the third vein beyond 

 is gently bisinuate. The last section of the fourth vein is sinuate like it 

 is in Sj/ritti(, but more deeply so, the vein terminating very near the 

 costa, but forming nearly a right angle at its juncture. 



The present genus must be placed in the vicinity of Paragns ; but yet 

 it is very diff"erent in the antennae, the abdomen and the wings. The 

 fourth segment of the abdomen is probably composed of two, as is 

 the third segment in Triglyplius ; it does not show any traces whatever 

 of such union on the dorsum, but I think I can distinguish it in the venter. 



Nausigaster puuctulata n. sp. 



5. — Length 12 mm. Black, moderately shining, everywhere except on legs 

 and venter covered with thick whitish pile, which, when not rubbed, leaves every 

 numerous, nearly contiguous circular black spots, more abundant on the thorax ; 

 on the dorsum of thorax and abdomen the ground color of the moderately shining 

 punctulate black surface maj be in large part denuded. In the middle of the 



