of the Amazon Valley. 401 
are modified from genus to genus in the Longicorn family, it is 
difficult to decide on the true position and relationship of the 
present group. In the general shape of the body, as well as in 
the form of the muzzle, thorax, and apex of the elytra, it seems 
to approach the genus Acrocinus. The antenne, however, are 
quite glabrous beneath, instead of being ciliated partially or 
wholly as in Acrocinus; and the fore tarsi of the ¢ are dilated 
and ciliated, instead of being simple. In the proportions of the 
apical joints of the antenne there is a great similarity between 
Polyrhaphis and the Anisocerine, the terminal joint in both 
sexes being extremely short compared with the penultimate. 
This seems to be a significant character. The form of the 
muzzle, too, is not greatly different from that of the Anisocerine; 
but the general form, the shape of the elytra and of the sterna, 
reveal no affinity with that group. The genus seems to have no 
close relationship with any other group of Lamiaires: it shows 
some resemblance to Acrocinus and the Anisocerine ; but many 
intermediate links are wanting to prove a genealogical relation- 
ship. The prosternum is extremely narrow in this genus, and 
the mesosternum is contracted in the middle between the 
haunches. The anterior acetabula gape widely on the sides, the 
sutures being opened along their whole length. The genus is 
a very natural or well-defined one, comprising a cluster of spe- 
cies which agree with each other in facies as well as in structural 
characters. They are all of large size, have greatly elongated, 
filiform, rather stout antennz, long and acute lateral thoracic 
spines, sometimes directed forwards, and ample oblong elytra, 
whose apices are broadly truncated and spined. 
1. Polyrhaphis spinosa, Drury. 
Lamia spinosa, Drury, Illustr. ii. p. 60, pl. 31. f. 3 (1773). 
Cerambyz horridus, Oliv. Ent. iv. 66, pl. 4. f. 29 (1789-1808). 
Lamia horrida, Fabr. Ent. Syst. i. ii. 273. 25 (1792). 
The figures given by Drury and Olivier agree well in shape 
and form of the spines with the insect I have before me, taken 
at Villa Nova, on the Lower Amazons. My example, however, 
appears to be of a lighter colour. The general hue of the to- 
mentum is hoary or ashy, the elytra, with the exception of the 
basal and apical parts, being of a violet-brown colour. The 
shape of the elytra in this species is elongate-quadrate, being 
only slightly narrowed posteriorly, with the base and apex rect- 
angular, and the sides nearly straight. The spines on the elytra 
are as follows :—a row of small ones placed close to the suture, 
but deficient near the base and the apex; three large ones on 
the centro-basal ridges, two on the shoulders, and five or six 
very long ones on the disk. It occurs in Guiana as well as the 
