CORTHYLI. 249 
The diagnosis of the Corthyli is given on page 185 of this work; but the 
peculiarities of the tibial structure there mentioned are scarcely constant, as in some 
genera, especially Corthylus, there are the faintest indications only of any roughness 
on the outer face of the tibia. The head is devoid of rostrum and is sometimes 
entirely hidden by the prothorax; the forehead may exhibit important sexual 
characters; the eyes, often large, are deeply emarginate and rather coarsely granulate. 
The funiculus is very short, with from one to three joints, a feature distinguishing 
the Corthyli from other Tomicides, except a few genera such as Crypturgus and 
Aphanarthrum, which differ in other structural characters and in general appearance. 
The basal joint, alone present in Corthylus, is cupulate; its apex is closely applied to 
the base of the club, and the intervening suture may at times appear evanescent or 
wholly obliterated. Examples are met with in which examination either fails 
positively to determine the number of joints or leads (as in two specimens of 
Amphicranus in our collection) to a result not in accordance with the normal character 
of the genus. 
Such phenomena, observed in unique examples, are not necessarily constant in the 
species, and perhaps would be found not to exist if the antenna could in such cases 
be examined after mounting in balsam as a translucent object. They may have their 
origin in defects of observation alone. Their effect, however, is (as in Hypothenemus, 
anted, p. 226) to diminish, though not wholly to destroy, the value to be placed on the 
number of joints as a trustworthy generic character. | 
It may be concluded, both for this and other subgroups, that a species (or 
individual) exhibiting a reduction in the number of funicular joints from that found 
in its nearest allies is not, in the absence of other appropriate differences of structure, 
generically distinct; whereas one that possesses a number in excess of its allies may 
be expected to manifest such other distinctions as will justify its generic separation. 
The antennal club is moderate or large, sometimes very large, and flattened ; ovate, 
acuminate, elongate or asymmetrical in shape, with two well-marked sutures and 
usually traces of a third, all more distinct on the outer than on the inner face. The 
latter, when the club is well-developed, is concave; and both faces are shortly 
pubescent and may be furnished (perhaps in the females alone) with fringes or 
fasciculi of long straight or curved hairs. | 
The mouth-parts are of the type associated with the wood-boring and ambrosia- 
feeding habit, having the maxilla fringed with fine sete and the apical joint of the 
labial palpus longitudinally striate; those of the principal genera have been fully 
described by Eichhoff. 
The prothorax has the flanks more or less impressed, and frequently an elevated 
margin along the sides and hind angles. Its anterior half is roughened by asperities, 
usually of the form which would be produced by making very oblique incisions into 
a ball of soft wood, so as to raise small cusps over the surface, ‘The posterior half 
BIOL. CENTR.-AMER., Coleopt., Vol. 1V. Pt. 6, November 1904. Q9KK 
