of the Amazon Valley. 453 
quite impunctate; the disk tawny brown; the sides yellowish. 
Elytra very broad at the base, the breadth at that point being 
three-fourths the length; they are very gradually narrowed to 
two-thirds the length, thence more rapidly narrowed to the apex; 
each has in the middle, near the base, a very large naked obtuse 
tubercle; behind this, on the disk, are four short raised longi- 
tudinal lines, the one nearest the suture only being strongly 
elevated ; the basal two-thirds of the surface is scantily covered 
with granulated punctures, mostly arranged in lines, each of 
which is accompanied by a dark-brown speck; the colour is 
ochreous brown or tawny; the posterior part of the suture and 
the discal ridges are finely streaked with grey; behind the 
middle is a broad irregular dark-brown belt, preceded by a yel- 
low line; the dark-brown colour runs from the belt along the 
margins and suture to the apex. The body beneath and legs 
are clothed with greenish-yellow pile, which is denser on the 
sides of the breast and on the tarsi. The fore tibiz are dilated 
and compressed. 
One example, taken on the trunk of a tree at Tunantins, on 
the Upper Amazons. This and the following have a most de- 
ceptive resemblance to species of Curculionidee of the genus 
Cratosomus, which occur in numbers on the trunks of certain 
trees. The general colour is exactly the same, and the resem- 
blance is made more perfect by the large, glossy, basal tubercles 
of the elytra, which are merely modifications of the ordinary 
centro-basal ridges existing in this section of the Lamiaires. 
The shortness and slenderness of the antenne, rendering the 
organs almost invisible at a short distance, also assist in perfect- 
ing the disguise, which completely deceived me when I saw the 
insect in situ. G. scabripennis (Serville), a native of Cayenne, 
belongs to this same group, all the forms of which appear to be 
excessively rare. 
4, Gymnocerus crassus, 0. sp. 
G. ovalis, convexus, tomentosus ; thorace elytrisque fulvis, his fascia 
latissima et macula subapicali canis. Long. 83 lin. 9. 
This species very much resembles the preceding, and might 
be treated as a variety of it, although it seems more convenient 
to deal with it as a separate form. The punctures of the elytra, 
with the granulations, are much more strongly developed; 
otherwise the only differences observable are those of colour. 
The head is greenish yellow, with the crown and occiput grey. 
The thorax does not differ from that of G. cratosomoides. The 
base of the elytra is occupied by a narrow belt of a fulvous co- 
lour, and a much broader belt of the same hue crosses the elytra 
behind the middle; the rest of the surface is hoary grey, with 
Ann, & Mag. N. Hist, Ser. 3. Vol. ix. 32 
