31 
(Consp. Insect. Peru., p. 143) ; but the latter is described as 
having the apex of the elytra armed with a very short spine. 
19. Acanthoderes bivitta. White. 
Sieirastoma bivitta, White, Cat. Long. Col. in Brit. Mus. ii. p. 354. 
This species was placed by Mr. White, whose description 
otherwise is a very good one, in the genus Sieirastoma. It 
differs from that group in having simple instead of complex 
lateral thoracic tubercles. It stands in certain French collec- 
tions as A. tardigradus of Dejean’s Catalogue. It is a common 
insect, in the Upper Amazons, on the trunks of felled trees of a 
certain species, to whose bark its colours are assimilated. It is 
found also in French Guiana. It is inactive in its habits, but 
appears to be extremely prolific. The opposing faces of the pro- 
and mesosterna are steeply inclined and bituberculated. 
§ 2. Antennae with the terminal joints thiekened and ciliated in the males, 
or triangularly dilated in both sexes ; the third or third and fourth 
joints often furnished with tufts of hairs. {Pteridotelus, White, in 
part.) 
[Although so diversified in structure and ornamentation of 
antennse, this group is homogeneous in the form of the body, 
sterna, and in other respects.] 
20. Acanthoderes spectabilis, n. sp. 
A. eloiigatus, subdepressus, postice attenuatus, niger, velutinus, ma- 
culis magnis albis ornatus : antennarum articulo tertio scopa 
magna nigra instructo. Long. 8 lin. S $ . 
Head black, with a triangular white spot in the middle of the 
forehead, two between the antennse of the same colour, and two 
rounded on the vertex. Antennse black, base of the fourth and 
following joints grey, the third joint encircled by a thick brush 
of black silky hairs, which extends nearer to the base on one 
side than on the other. Thorax with the lateral and dorsal 
tubercles large, conical, and acute ; velvety-black, with two large 
rounded spots on each side, two elongate ones on the fore part, 
which are divergent behind, and another in the middle of the 
hind margin, white. Elytra elongate- trigonal, depressed toge- 
ther down the suture, the apex obliquely sinuate-truncate, outer 
angles acute ; the centro-basal ridges much raised at the base, 
projecting over the hind edge of the thorax, prolonged behind 
to the apex, and granulated at their commencement ; the surface 
impunctate, except on the suture near the base ; the colour is 
velvety-black, each elytron having two spots along the suture 
behind the scutellum, a broken sutural stripe from the middle 
