450 Mr. H. W. Bates on the Longicorn Coleoptera 
Elytra at the base reddish brown and granulated, each with two 
rounded spots, and the humeral callus black; the rest of the 
surface has four rows of quadrate black spots divided only by 
narrow lines of a reddish-brown colour, and before the apex is a 
transverse black streak; the spaces between these black spots 
are quadrate in shape, and of a pale ochreous hue. Abdomen 
beneath varied with black. This variety diverges from the type 
only in the increased size and squared shape of the black spots, 
and the pallid hue of the equally squared interspaces. It is 
intermediate both in character and in geographical position be- 
tween the type and local var. 0, and is found near Fonte Boa, on 
the Upper Amazons. 
Local var. 6. A. Olivencius. Much larger than the type, being 
7-74 lines in length. The occiput is black, with two pale 
ochreous lunate spots behind the eyes. Elytra at the base dingy 
ochreous and granulated, each with two rounded spots, and the 
humeral callus black; the rest of the surface is dark violet- 
brown, with four rows of angular spots, and the tip pale ochreous; 
the black spots in the same positions as in the type appear faintly 
through the violet-brown ground-colour. The rest as in the 
type. In this variety the pale spots of the elytra, already indi- 
cated in var. a, are strongly marked, and the ground-colour has 
become obscure. This change in the dress, added to the mark- 
ings of the head and the size and robustness of the whole body, 
give the variety an aspect totally different from the typical form. 
Taken sparingly at St. Paulo de Olivencia: all the individuals 
found were conformable to the description here given. 
This pretty insect seems very susceptible of local modification. 
The typical form is confined im its range to a very limited area 
around the town of Ega, on the Upper Amazons. It is there 
found in plenty on the trunks and branches of fallen trees in 
the virgin forest. At Fonte Boa, 120 miles above Ega, it occurs 
under a slightly modified local form (A. Fonteboensis), which 
would be scarcely worthy of remark were it not intermediate 
between the Hea type and the strangely transformed local variety 
or race, A. Olivencius, found at St. Paulo, 180 miles further west, 
or 800 miles in a straight line over a uniform country undivided 
by physical barriers from the home of its type. As before re- 
marked, when a species varies in this way from district to di- 
strict not far apart, it often happens that several closely allied 
but more distinct forms or species present themselves in districts 
further removed; these may be fairly suspected of being also 
modifications, considermg the proof already obtained. of the 
variability of the species. Several of these nearly allied forms 
occur in the present case. Thus I have no doubt, on perusing 
the excellent description, that the A. stel/atus of Guérin-Méne- 
