of the Amazons Valley. 313 



punctured, except at the extreme apex. The antennas are closely 

 approximated at the base, the bases of the tubercles being sepa- 

 rated only by the impressed line on the vertex; the angles of 

 the tubercles are not produced. The antennas are more than 

 twice the length of the body in the male, the apical joint being 

 twice the length of the preceding, and of great tenuity ; in the 

 female they are but little longer than the body, but the apical 

 joints are very slender and more elongated than is usual in the 

 female sex of Longicorn insects ; the basal joint is as long as 

 the third, and clavate at the apex. 



Found, rather commonly, on slender branches on the banks 

 of the Tapajos, and also at Ega. 



Genus Peritrox, nov. gen. 



Body subcylindrical. Head moderately narrow; face plane, 

 inclined obliquely backwards; eyes ample, convex ; antenniferous 

 tubercles with their inner angles produced. Antennas elongated, 

 simple; basal joint gradually thickened from the base; third 

 joint straight, one-fourth longer than the first, fringed beneath 

 with fine hairs. Thorax subcylindrical, uneven, sides armed 

 with prominent, acute lateral tubercles. Elytra cylindrical, free 

 from ridges and tubercles; apex rounded. Legs moderate; 

 thighs clavate ; claw-joint of tarsi greatly elongated, longer than 

 the three remaining joints taken together. 



This new genus, founded on one species only, is very closely 

 allied to Trestonia, differing, in structural characters, chiefly in 

 the gradually thickened basal joint of the antennas. The cha- 

 racteristic feature in the coloration of the elytra of Trestonia is 

 entirely absent, the colours being dull and uniform. In form 

 of body and head, the species described below resembles much 

 Trestonia terminata and T. coarctata. 



Peritrox denticollis, n. sp. 



P. subcylindrica, paulo convexa, fuliginosa ; elytris maculis tomen- 

 tosis fulvo-brunneis adspersis ; capite inter antennas profunde 

 impresso ; thorace transverse ruguloso, lateribus acute tubercu- 

 latis. Long. 5 lin. <$ . 



Head sooty black, coarsely punctured on the forehead and 

 crown, and deeply grooved between the antenniferous tubercles, 

 which are closely approximated at their bases, and have their 

 inner edges produced into short ear-like lobes. Antennas 

 blackish, shining. Thorax subcylindrical, surface uneven, and 

 marked with a few sharp transverse wrinkles, besides two 

 impressed lines parallel to the hind margin ; lateral tubercles 

 conical, acute ; colour sooty brown. Elytra cylindrical, narrowed 



