380 Mr. T. Vernon Wollaston on 



tot approximati," which would imply (if indeed anything decisive 

 can be extracted from the expression), that all the legs are 

 equally distant (and hut very slightly so) at their base, can have 

 no meaning at all in the present and neighbouring groups, — in 

 which (like most of the Cosso7i'uh's) the anterior pair are but very 

 little separated from each other, the intermediate ones a good 

 deal more so, and the hinder pair excessively distant. 



Although members of tlie same sub-family, and possessing a 

 5-jointed funiculus, the M'lcroxyloh'u are essentially distinct from 

 the Peniart/ira, and may be regarded as a little geograjjliical 

 assemblage, in all probability (like the Catdotnipides, in Madeira) 

 peculiar to St. Helena. Apart from their very great differences 

 of outward configuration, and the spiniferous femora of some of 

 them, they may be known from the true Pe/iiarthrn (which are 

 narrow, cylindrical, linear, deeply sculptured insects, like Mcsites 

 and Cussonus), by their obsolete scutellum, and more elongated 

 limbs and rostrum, — the latter of which is, moreover, less 

 straightened, and with the antennae inserted much nearer to its 

 apex ; whilst the antennae of the typical Pentarihra are (in both 

 sexes) strictly vicd'ud, or (if anything, perhaps) implanted a 

 trifle even behind the middle, rather than before it. 



It would seem, indeed, that there is a small chisler of Cosso- 

 nideous groups with 5-jointed funiculi ; for, now that I liave 

 lately received, through the indefatigable researches of Mr. 

 Bewickc, a second species of Pcnlarthrum proper from the island 

 of Ascension, I have no hesitation wliatsoever in regarding the two 

 weevils from Madeira and the Canaries, wliich (through a disin- 

 clination to multiply genera) I had lately registered* as aberrant 

 Pcntarthra, as a separate genus (for which in the present paper 

 I have proposed the name of Mesoxenus'), — characterized by its 

 almost obsolete eyes, and differing from Pentarihriim jnoper in 

 the more co)ivex, fusiform, cscutellale bodies, less straightened 

 rostra, and more apically inserted antennae of the insects which 

 compose it ; and from the St. Helena Microxylobius (to which, 

 perhaps, it is more akin), in the smaller size and unmetallic sur- 

 faces of its two hitherto detected representatives, — which, more- 

 over, have a less dilated antepenultimate tarsal joint, their 

 antennae implanted a little further from the apex of their rostrum, 

 and no tendency w'hatever for the above-mentioned anomalous 

 femoral spines. So that, if my premises be correct, we shall 



* Vide " Annals of Natural History" (1860), wliere these two insects are de- 

 scribed, under the names of Pentut thrum Muimhinnm and nenick'tuiium respec- 



tivtl)'. 



