Genera of the CossonidcB. 513 
very peculiar rostrum of the latter, wliicli Is curiously 
pinclied-in (or suddenly constricted) at its base ; and it is 
likev^dse smaller and more cylindrical (tlie protlioi'ax being 
proportionately wider, and the elytra more parallel), of a 
darker hue and didler surface, with its metasternum and 
limbs more abbreviated, and with the first joint of its feet 
less elongate, and the third one more decidedly simple. 
12. Xenosomatium {nov. gen.\ — The very minute 
Pentarthrid for which I have established the present 
genus has been communicated by Mr. Pascoe, and was 
captiu'ed by Mr. Wallace in the Malayan archipelago. 
Apart from its diminutive size and 5-articulated funiculus, 
its greatly abbreviated second fuuiculus-joint, and its 
abrupt, largely developed club, it is at once remarkable 
for the structure of its tibise, — which are rather short, 
broad, and triangular, and have their terminal hook in the 
four posterior ones abbreviated, straight, and spiniform, 
but still shorter (in fact obsolete) in the front pair (where 
it is replaced by a robust and o?<^wardly-curved pubescent 
spine which arises firom the inner angle). This tibial 
modification is very peculiar, and one which I do not re- 
member to have observed in any other Cossonideous group. 
In minor details Xenosomatium is conspicuous for its 
(somewhat short, broad, and arcuated) rostrum being a 
good deal constricted at the base, behind the insertion of 
the antennas (which arise nearer to the base than is usual 
in the Pentarthrideous types ) ; for its scape being long 
and backwardly-curved, as well as greatly clavate (though, 
at the same time, obliquely lopped-off at the inner apex) ; 
for its eyes being extremely large and jirominent ; and for 
its feet having their first three joints thickened and sub- 
equal, but the ultimate one rather slender. In its piceo- 
feiTuginous hue Xenosomatium agrees with the majority 
of these immediate forms, but its sculpture is finer and 
lighter than is usually the case. 
13. Pentarthrum (WoUaston, Ann. Nat. Hist. xiv. 
129. 1854). — Judging fi-om the twelve exponents which 
have hitherto been brought to light, the Pentarthra are 
more or less narrow and parallel insects, closely sculptured, 
nearly always free from scales and pubescence, either 
piceous or castaneous in hue, and but very slightly shining. 
Their eyes are prominent, and, together Avith the scutellum, 
conspicuous ; their prothorax is rather large, and, like the 
