ART. 16 NORTH AMERICAN ICHNEUMON-FLIES CUSHMAN 53 



notum laterally rugose, mesoscutum and scutellum sparsely punc- 

 tate, mesopleurum above longitudinally striate, below sparsely punc- 

 tate, sternum and metapleurum densely punctate, speculum and 

 lower angle of upper division of metapleurum polished and unsculp- 

 tured; notauli complete; propodeum polished before basal carina 

 opaque reticulate regulose behind, apophyses represented by low 

 rounded tubercles. Abdomen opaque, very finely coriaceous, first 

 tergite polished, sheath distinctly shorter than first segment. 



Head *and thorax piceous black and yellow, the yellow more ex- 

 tensive than the black, embracing the following: Head except middle 

 of frons and vertex and occiput; under side of scape; an incomplete 

 annulus on flagellar joints G-11 (antennae otherwise black) ; all of 

 pronotum except a narrow transverse band across middle; inner 

 posterior edges of lateral lobes of mesoscutum and the outer anterior 

 edges of middle lobe ; scutellum, its basal carinae, and postscutellum ; 

 tegulae and subalar tubercles; most of mesopleurum, sides of 

 sternum, and both divisions of metapleurum; propodeum beyond 

 basal carina except lateral anterior corners and a small median apical 

 spot; prepectus and mesosternum reddish; legs testaceous; front and 

 middle tibiae and tarsi stramineous; hind tarsus blackish at base 

 and apex, first joint largely, second entirely, and third apically 

 white; wings hyaline, venation blackish; abdomen ferruginous, base 

 of petiole and second and third tergites except broad apical and 

 lateral margins blackish. 



Type-locality. — Brownsville, Tex. 



Type.—C2it. No. 40592, U.S.N.M. 



One specimen taken September 29, 1906, J. C. Crawford. 



ACERASTES, new genus" 



Very closely related to Poly cyrtidea Viereck and should, perhaps, 

 be considered merely a subgenus of that genus. But the genotype 

 and two apparently undescribed Neotropical species differ from the 

 three species of Poh/cyrtidea in lacking the frontal horn and in hav- 

 ing the areolet rather large, well defined, and pentagonal, though 

 open behind, with the recurrent before the middle and the cubitus 

 beyond the recurrent weak and bent sharply forward at recurrent and 

 then sharply backward at the position of the second intercubitus. 



Genotype. — Mesostenus pertinax Cresson. 



Three specimens of one of the undescribed species referred to were 

 reared from a spider egg-sac. 



Represented in the United States only by the genotype. 



• From a-)«pQaTi7s=without a horn, referring to the lack of a frontal horn. 



