199 
basi valde approximatis, articulo basali elongate, apice abrupte 
clavato ; elytris crebre punctatis, apice nigris, fulvo lituratis. 
Long. 4^-6 lin. J 2 • 
The form of body and situation of the dark apical spot (close 
to the apex of the elytra) in this species so closely resemble the 
same features in the figure above quoted of T, terminataj that it 
is not unlikely the specimens here treated of belong to that 
species. I cannot, however, reconcile the description of the 
colours given by M. Buquet with my insects ; and the figure is 
as uncertain in this respect as the description. His words are, 
‘^Couleur generale d’un gris-verdatre melange de blanc et par- 
fois de jaunatre sur le devant de la tete, sur les bords lateraux 
du prothorax et sur la partie inferieure des elytres.” The head 
in all my specimens is of a pale ashy hue, with a dark-brown 
spot on the upper part of the forehead between the eyes. The 
elytra as well as the thorax are dark brown, clothed with thinnish 
ashy pile, and sometimes varied with tawny, and becoming of a 
paler ashy hue near the dark apical spots. The thorax has a 
number of large scattered punctures, and the elytra are thickly 
punctured, except at the extreme apex. The antennae 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 antennae 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. Antennse 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 
