146 U.S. NATIONAL MUSEUM BULLETIN 261 



Thorax with width less than transocular width of head, lateral 

 margins slightly divergent anteriorly, posterior two-thirds of disc trans- 

 versely striate, without pubescence, posterior margin concave, with 

 very strong dorsopleural carinae which are rectilinear or curved slightly 

 ventrally at midlength; scutellum transversely striate on posterior 

 portion. Forewing without a membrane, veins distinct or not, surface 

 coriaceous, with only four apical cells, the base of the third located 

 more distally than base of fourth, without an anteapical plexus of veins 

 in corium and without anteapical supernumerary veins to costal 

 margin, wings of female at rest scarcely attaining apex of ovipositor. 

 Hindwing extending almost as far posteriorly as forewing, with vein 

 R2+3 incomplete. Hindlegs with femoral setal formula 2:0:0; first 

 tarsomere not longer than combined length of second and third. 



Male genitalia: Pygofer moderately produced posteriorly, broadly 

 to narrowly rounded at apex, with a few anteapical macrosetae or with 

 numerous microsetae on posterior two-thirds of disc, without processes. 

 Plates separate throughout their length, which is variable inter- 

 specifically with relation to pygofer apex, triangular, with numerous 

 dispersed microsetae. Connective somewhat Y-shaped, with a median 

 keel. Style extending posteriorly as far as or farther than apex of con- 

 nective, with distinct preapical lobe, truncate or foot-shaped at apex. 

 Aedeagus symmetrical, of moderate length, not curved dorsally, without 

 processes. Paraphyses present, with paired basal and paired apical rami. 



Female abdominal sternum VII with posterior margin transverse, 

 ocasionally slightly emarginate at middle. 



The greatly modified head in Ochrostacta separates it readily from 

 other genera in the tribe. Its relationships to other genera are unknown. 

 On the basis of the head alone, the two species might readily be placed 

 in different genera, but the heads arc alike in being bizarre, and the 

 forewings and male genitalia have a number of similarities. The genus 

 is known only from southeastern Brazil, northern Argentina, Uruguay, 

 and Paraguay. 



SPECIES OF OCHROSTACTA 

 [*Type not seen.] 



*diadema (Burmeister), I835a:120 {Tettigonia) . SE. Brazil. 

 physocephala (Signoret), 1854d:720 {Tettigonia). Paraguay, N. Argentina. 



KEY TO SPECIES OF OCHROSTACTA 



Antennal ledges very strongly protuberant, crown coarsely pitted 

 anteriorly, with a lateral apical process on each side. 



O. diadema (Burmeister) (fig. 135) 



Antennal ledges not strongly produced, crown glabrous anteriorly, 

 without such processes . . O. physocephala (Signoret) (fig. 136) 



