176 RHYNCHOPHORA. 
prothorax, being visible from above. The eyes are large, but not contiguous above ; 
below they extend along the buccal borders, and are narrowly separated on the gular 
space. The antennal funiculus is 6-jointed as in the other Hexacolides, and not 5-jointed 
as described by Chapuis; the club is crossed by two slightly oblique sutures, the basal 
one being strongly chitinized towards its outer part as in Phlwosinus. The maxillary 
lobe is narrow, the palpi have the first two joints strongly transverse, the third as long 
as broad. The mentum is oblong, narrowed and incurved at the base, the ligula is 
attached about its middle, and is narrow and pointed; the labial palpi are moderately 
long, the joints somewhat inflated, scarcely transverse and not hairy. 
The prothorax is uniformly and gently convex above, entirely devoid of asperities, 
and narrower than the elytra, which are slightly rounded but not margined at the base. 
The anterior femora are long and dilated ; the middle and hind pairs are narrow. 
The species are small, oblong insects, covered with scales and hairs, distributed 
thinly on the prothorax, which is margined with outstanding scales, and more closely 
on the elytra, which possess rows, sometimes irregularly biseriate, of conspicuous 
interstitial scales. The large outwardly projecting fore-femora are also characteristic 
of these insects. 
The genus is one of the hardest of all Scolytid genera to study. ‘The differences 
between the species, of which there appear to be several, consist merely of slight 
modifications in shape, colour, vestiture, and depth of punctuation; and, in the 
absence of more exact differential characters, the task of delimitation appears to be 
quite hopeless, except by an exhaustive comparison of long series in good condition. 
Chapuis has described two species from Mexico and Guadeloupe respectively, Ferrari 
one from Cuba, C. O. Waterhouse one from Fernando Noronha. Eichhoff has also 
described a couple, one at least of which is synonymous with one of Chapuis’s. The 
genus appears to be generally distributed over Tropical America and the Antilles. 
1. Pycnarthrum lambottei. (Tab. VII. figg. 2, antenna; 24, fore-leg.) 
Nemobius lambottei, Chap. Syn. Scol. p. 42* (Mém. Soc. Liége, 1873, p. 250). 
Pycnarthrum quadraticolle, Eichh. Rat. Tom. p. 106°. 
Hab. Mexico 2, Teapa 1, Orizaba and Cuernavaca (Bilimek); GuaTeMAua, San Juan in 
Vera Paz, San Gerénimo, Zapote (Champion). 
This species is somewhat variable, the examples from San Gerdnimo being larger and 
finer than those from Mexico. ‘The prothorax is about as long as broad, parallel-sided 
for the hinder two-thirds, incurved in front; the interspaces between the covering of 
scales are shining. The elytra are about two-thirds longer than the prothorax, with 
subimpressed rows of very large deep punctures, varying in number in different 
specimens; the scales are yellowish-grey, the prominent series on the interstices 
occurring, for the most part, in very irregular double rows, except on the declivity. 
