180 RHYNCHOPHORA. 
of the prothorax give the insect the appearance of possessing a thick callosity on each 
side, but the surfaces from which they spring are depressed and not elevated. The 
specimens show no sexual differences. 
HEXACOLUS. 
Hexacolus, Eichhoff, Berl. ent. Zeitschr. 1867, p. 399; Rat. Tom. p. 306. 
In this genus are included several species which vary amongst themselves in shape 
and in various minor points, but which agree on the whole with the type-species, 
H. glaber, Eichh. They differ from Prionosceles in the possession of comparatively 
narrow and non-dilated tibie, the armature of which is much more feeble; the anterior 
pair bave two well-marked curved spines at the apex. The prosternal process is not 
broader than long; the 3rd and 4th abdominal segments are less short. The joints of 
the antennal funiculus appear to be somewhat variable in proportion in the different 
species, and the club varies in shape and the arrangement of the sutures, but these 
points are very difficult to ascertain exactly unless the antenna is mounted in balsam. 
The prothorax is little or not at all narrower than the elytra, and is bordered at the 
base in ZH. glaber, but not distinctly so in the smaller Central-American species ; 
the lateral margin is, however, well marked, and the sides are without trace of the 
depression found in Lpomadius. 
It is possible that Bostrichus levigatus of Dejean’s catalogue, which has been made 
the type of two genera, Scolytodes, Ferr., and Ctenophorus, Chap., may have eventually 
to be referred to this genus. It differs in the relatively narrow prothorax, which is 
scarcely declivous in front and is devoid of all asperate punctures, and in the extremely 
fine teeth of the middle and posterior tibiz, which are not visible without powerful 
amplification. According to Chapuis, the fifth joint of the funiculus is smaller than 
the fourth or sixth; I cannot make out this in his or Ferrari’s type-specimens. The 
difference in size, if existent, is very slight and probably quite unimportant. 
The number of species of Hexacolus occurring in Tropical America and the Antilles 
is evidently large, and when more have been studied it will be appropriate to decide 
whether further subdivision of the genus is necessary. 
The four species from Central America may be thus distinguished :— 
1. Prothorax and elytra pubescent, the former evidently the narrower . .  setosus, sp. n. 
Prothorax and elytra entirely glabrous, about equal in width . . . . 2, 
2. Form oblong; testaceous with the apex of the prothorax and suture of 
° 
the elytra black 
Soe ee ee » + « . melanocephalus, sp. 0. 
Form subelongate ; unicolorous or with the disc of the prothorax lighter 
in the middle, last abdominal segment with two sete. . . . . . 8. 
3. Base of the prothorax punctured, elytra with impressed strie . . . unipunctatus, sp. n. 
Base of the prothorax impunctate, elytra with rows of very fine punctures. piccus, sp. n. 
x 
