57 
of twenty miles of Ega, on the Upper Amazons. At Nauta, 
540 miles to the west of Ega, the species recurs in a modified 
state ; the modification is one of colour only, but is remarkable 
for its distinctness and its occurring in both sexes. The follow- 
ing is a short description of it : — 
Local var. A. Nautensis; 8 lines, 6 $ . 
The white fascia of the elytra is very much broader ; the se- 
cond black belt extends posteriorly along the suture, and the 
tooth-shaped black streak near the apex is replaced by a distinct 
isolated round spot. 
I received one pair of this variety from Nauta, on the banks 
of the Upper Amazons, in Peru. 
Genus Onychocerus, Serv. 
Serville, Ann. Soc. Ent. Fr. iv. 83. 
In this genus the antennse have eleven joints in both sexes, but the 
terminal joint is much thinner than the others, and claw-shaped. 
In the males several of the apical joints are fringed beneath 
with long hairs; the second joint in both sexes is remarkably 
elongated. The sterna are in some species simple, and in others 
tuberculated, showing that this character has no generic value ; 
for this genus is one of the most natural of the whole tribe. 
The tarsi of all the legs are strongly dilated ; the fore tarsi of the 
males are more widely broadened than the others, but they are 
not fringed with long hairs. The ligula is elongated, not dilated 
on the sides, but simply rounded; the two lobes approximate, 
but are not united on their inner edges. 
1. Onychocerus scoi'pio, Fabricius. 
Lamia scorpio, Fabr. Maiit. Ins. i. 131. 8. 
, Fabr. Ent. S}'st. i. ii. 273. 26. 
This well-known and common species is always found on the 
trunk of a particular kind of wild fruit tree called by the natives 
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^ n. sp. 
O. ovalis, postice paulo dilatatus, cinereo-fuscus : elytris multituber- 
H 
