IIO STUDIES IN NORTH AMERICAN MEMl'.RACID/E 



the abdomen. In perdita this process does not attain the mid- 

 dle of the abdomen, but perdita evidently pertains to Fowler's 

 genus the characters of which should be so modified as to 

 admit it. 



Genus Platycentrus Stal. 



Platycentrus acuticornis Stal. 



In the Cornell University lot are two good typical examples 

 of this species from Arizona and another with the horns shorter 

 and more depressed, the latter bearing the MS name Diaper ops 

 furcatus Uhler. Another specimen from California has the 

 horns still shorter and stouter, the pronotal surface more cast- 

 aneous with less conspicuous rugae, and the tibiae darker at apex 

 without the pale bands. This specimen is probably near the 

 form from Jalisco mentioned in the Biologia. I cannot distin- 

 guish it specifically from acuticornis with the material in hand. 



Genus Tylocentrus n. gen. 



Allied to Sphcerocentrus Fowler. Short, robust; pronotum 

 but little elevated, subglobose, depressed and rounded Defore. 

 Humeri subangularly prominent, the rounding sides above the 

 humeri armed in the female by a short, abrupt, and acute 

 suprahumeral spine, in the male unarmed ; Posterior process 

 reaching to about the middle of the abdomen, abruptly nar- 

 rowed at base, then parallel for a space, its apex acute, nearly 

 one half the width of the scutellum. Scutellum broad, appar- 

 ently bidentate at apex. Elytra free, coriaceous at base, areoles 

 beyond the middle irregular, with more or less complete anasto 

 mosing veinlets; discal areoles apparently three, apical four. 

 Head short, transverse, the clypeus abruptly protracted for 

 most of its length beyond the line of the cheeks; obviously 

 widened and in the male recurved at apex. Tibiae simple. 



This genus is proportionately shorter that Sphcerocentrns. 

 The posterior process is much shorter and is appressed to the 

 surface of the scutellum, and the dorsal line when viewed from 

 the side is almost straight or at most but moderately sinuated. 

 From Tiibercidocentrus Goding it differs in its broader form, 

 the presence of suprahumeral horns in the female of the type 

 species at least, the shorter and less sinuated posterior process 

 of the pronotum, and in the less strongly reticulated elytra. 



