268 PROCEEDINGS OF THE ACADEMY OF [PaRT II 



dition of many features of the early stages. The macropterous 

 males show the usual differentiation from the early stages developed 

 by adults of the normal macropterous species of Ischno'ptera. 



The close agreement of the brachypterous males and females 

 offers ample evidence that they represent a single species. The 

 macropterous males are assigned to the same species through their 

 close similarity in genitalic characters, limb armament and color- 

 ation, the differences shown being wholly attributable to the fac- 

 tors discussed above. 



Type: cT ; Carcarana, Santa Fe, Argentina. [Hebard Collect- 

 ion Type no. 704.] 



Size small, form rather slender for the genus. Interocular space 

 broad, as wide as that between the antennal sockets. Ocellar spots 

 moderately large, though small and poorly defined for the genus, 

 the area which they occupj^ not sharply delimited from the inter- 

 ocular-ocellar and rounding into it. Maxillary palpi with fourth 

 joint three-quarters as long as third, third joint three-quarters as 

 long as the elongate fifth joint. Latero-caudal sulci of pronotal 

 disk deep and strongly defined. Tegmina and wings extending 

 well beyond the cereal apices. Wings with a small intercalated 

 triangle, ulnar vein with (3) incomplete and (1) complete branches. 

 Dorsal surface of abdomen specialized as characteristic of genus. 

 Supra-anal plate symmetrical, trapezoidal with angles rounded, 

 width between cerci about twice length, surface weakly concave 

 except above cereal bases and meso-distad on each side where it is 

 weakly convex, distal margin transverse, showing weak lateral 

 convexity and very broad and weak median emargination, so that 

 a sub-bilobate condition is developed; ventral surface with a very 

 delicate transverse ridge between cereal bases and supplied distad 

 with elongate hairs. Paired plate beneath supra-anal plate de- 

 veloped into very large, flattened lobes; the sinistral formijig an 

 unarmed transverse ridge toward its dorsal margin, the dextral 

 with a heavier transverse ridge mesad, this ridge, as well as the por- 

 tion of the plate ventrad, armed with a number of minute but stout 

 spines. Titillator elongate and very slender, widening slightly be- 

 fore the aciculate apex but unspeciahzed. Subgenital plate with 

 surface strongly convex, 'except in produced area where it is 

 weakly concave; sinistral margin oblique and rather strongly con- 

 cave to median portion, dextral margin oblique and more broadly 

 concave a greater distance, the portion of the margin between being 

 short, straight, transverse. Sinistral style situated on sinistral mar- 

 gin mesad of the cercus, simple, cylindrical, weakly tapering to the 

 sharply rounded apex, with shaft weakly decurved, covered with 

 coarse hairs as is the subgenital plate. Dextral stjde situated me- 

 sad on the short, transverse distal margin, very similar but slightly 

 shorter, with decurvature slightly greater and apex slightly blunter 



