Genera of the Cossonida. 525 



are also more fusiform, or less parallel, insects than the 

 Pentarthra ; their prothorax is more rounded and convex ; 

 their elytra are less straightened, and more lightly sculp- 

 tured ; their rostrum is a little longer and less robust ; 

 and their antennae (which are implanted a trifle nearer to 

 the apex of the latter) have their scape slenderer and 

 more curved. There is also a peculiarity about their 

 undersides (which is likewise the case in most of the 

 Microxylobii and Acanthomeri, as well as in Lampro- 

 chrus, and in many of the true Cossonides), the first 

 abdominal segment and the (very short) metasternum being 

 deeply impressed (at any rate in the two Atlantic-island 

 species) down the central region, causing them to be 

 hollowed-out, or concave. Two out of the three Amau- 

 rorrhini with which I am acquainted (namely the A. 

 Monizianus and Bewickianus) are found in the 1 Madeiran 

 archipelago, and one of them likewise at the Canaries, 

 whilst the other occurs in the south of Europe ; but the 

 slight singularity in their modes of life, which appear to 

 be much the same as those of Pentarthrum (as well as of 

 Hexarthrum, of the true Cossonides), renders it probable 

 that they will be found eventually to possess a more ex- 

 tended range. 



28. PSEUDOMESOXENUS (nov. gen.\ The little insect 

 (hitherto unique) for the reception of which the present 

 genus is established was taken in the island of St. Helena 

 by Mr. Melliss ; and it was recorded by myself, three 

 years ago, as a blind, aberrant Pentarthrum, under the 

 name of P. subccecum.* It is evident however that it has 

 a far closer affinity with Amaurorrhinus, with which 

 indeed its obsolete eyes and scutellum, and its convex, 

 largely-developed prothorax, would tend to affiliate it. 

 Still, an accurate examination of its structural details has 

 convinced me that it cannot be treated as even an Amau- 

 rorrhinus ; for not only is its metasternum very appreci- 

 ably more elongated, and its rostrum thicker and sub- 

 triangular, but its elytra likewise are narrower and more 

 parallel and cylindrical, and its limbs are shorter and less 

 thickened, the feet especially being slenderer and filiform, 

 with their third joint almost unexpanded and simple. 

 The underside moreover is convex, and has no trace of 

 the concavity which gives so remarkable an appearance to 



* Vide ' Ann. Nat. Hist.' iv. 410 (1869). 



2 r 2 



