of the Amazon Valley. 455 
of the Amazon region Tapiriba ; and the strange sculpture, shape, 
and colours of the body and limbs of the insect give it a most 
wonderfully exact resemblance to the bark. It is not possible to 
distinguish the insect, although a very large one (sometimes an 
inch long and a third of an inch broad), unless the tree is care- 
fully examined. The tree is planted in fences very commonly in 
and near towns, on account of its rapid growth, and the insect 
accompanies it everywhere with the pertinacity of a parasite. It 
sometimes swarms on felled logs of Tapiriba. 
2. Onychocerus concentricus, ni. sp. 
O. ovalis, postice paulo dilatatus, cinereo-fuscus: elytris multituber- 
culatis, violaceo tinctis, lineis pallidioribus curvatis quasi concen- 
tricis ornatis. Long. 7 lin. ¢ 2. 
Head and antenne dull black. Thorax ashy brown, the sides 
below the lateral tubercles black; the disk punctured and tri- 
tuberculate. Elytra widest behind; the sides near the base 
thickly granulate-punctate; the upper surface furnished with 
about four rather distinct rows of large and small acute dusky 
tubercles ; ashy brown, the disk tinged with purplish, with se- 
veral rather indistinct curved belts alternately of a darker or 
paler hue; the first is dark, and near the base on the outer side 
of the centro-basal ridge; the second, pale, is exterior to the 
first, and strongly curved outwards; the third, more distinct, of 
a dark colour and strongly curved, touches the suture, and forms 
a semicircular belt common to both elytra. The body beneath 
and legs are black, and clothed with ashy-brown pile. The 
three terminal joints of the antennz in the ¢ have a few hairs 
beneath. The pro- and mesosterna are simple, the latter sloping 
from the hind to the fore margin. 
I found this species on one occasion only, in great plenty, on 
a felled tree at Caripi, near Para. The colour and sculpture of 
the insect gave it a deceptive resemblance to the bark on which 
it adhered. 
Genus XYLoTRIBUS, Serv. 
Serville, Ann. Soc. Ent. Fr. iv. 80. 
The antenne are short and mis-shapen ; the third and fourth 
joints are dilated on one side at the tip, the fourth much more 
broadly so than the third. The eleventh joint is long and slender 
in the @, short and subuliform in the 2. The head is narrow 
on the vertex, broadening below to the end of the muzzle, which 
is elongated. The terminal joint of the palpi is obtusely trun- 
cated at the tip. The ligula is short, slightly dilated in the 
middle, and the lobes joined together along their whole length, 
the two being conjointly and obtusely rounded at the apex. 
32* 
