Genera of the Cossonidas. 513 



very peculiar rostrum of the latter, which is curiously 

 ])inched-in (or suddenly constricted) at its base ; and it is 

 likewise smaller and more cylindrical (the prothorax being 

 proportionately wider, and the elytra more parallel), of a 

 darker hue and duller 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 

 captured by Mr. Wallace in the Malayan archipelago. 

 Apart from its diminutive size and 5-articulated funiculus, 

 its greatly abbreviated second funiculus-joint, and its 

 abrupt, largely developed club, it is at once remarkable 

 for the structure of its tibiae, -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 0wwardly-curved pubescent 

 spine which arises from the inner angle). This tibia I 

 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 prominent ; and for 

 its feet having their first three joints thickened and sub- 

 equal, but the ultimate one rather slender. In its piceo- 

 fcrruginoiis hue Xenosomatium agrees with the majority 

 of these immediate forms, but its sculpture is finer and 

 lighter than is usually the case. 



13. PENTARTHRUM (Wollaston, Ann. Nat. Hist. xiv. 

 129. 1854). Judging from 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 with the scutellum, 

 conspicuous ; their prothorax is rather large, and, like the 



