514 INSECTA MADERENSIA. 



Far. B. prothorax with the sides rather less sinuated than in any of the previous varieties, and with 

 its posterior angles somewhat obtuse. [Madeira ; in fissures of the rocks near the coast.) 



It must be admitted that the H. Vulcamis and confertus approach each other 

 very closely in most respects except in magnitude. Nevertheless they have small 

 peculiarities of theu- own, which, when pointed out, will be usually at once appre- 

 ciated even in those examples where theii" aberrations of size (ia contrary direc- 

 tions) would seem almost to meet : and, although I was originally iuclLued to 

 consider them as phases of one and the same species, yet a more accurate analysis 

 (of an extensive series, collected in different islands and at many altitudes), and, 

 above all, a careful observation of their habits in situ, has subsequently conviuced 

 me that they are trvdy distinct. In then" normal states there could never be any 

 hesitation, even at fii'st sight, in passing judgment upon them ; since the gigantic 

 dimensions of the H. Vulcaims (more than doubling the other), in conjimction 

 with its singularly rol)ust legs and antenna?, would of themselves suffice to charac- 

 terize it. But since both are of variable stature, it becomes necessary to be able 

 to recognise not the extremes only, but likewise the means. Howbeit we may 

 here premise that, even were occasional individuals to occur, out of a very large 

 number (which, so far as my own experience is concerned, has not hitherto 

 happened), in which real difficulty of identification would appear to exist, the 

 prolilem still remains unsolved, whether an exceptional link is to be regarded as 

 of sufficient importance to cause the amalgamation of otherwise well-defined forms ; 

 and whether a lusus NatiircB may not sometimes be the real explanation of what 

 might seem to us, when contemplated from an opposite point of view, to be con- 

 nective. I would merely mention tliis as a safeguard against a too hasty conclu- 

 sion in an instance like the present one, and not that the case (so far at least as I 

 have reason to believe) actually requires it, — since I have scarcely ever failed to 

 separate, and that too with j)erfect ease, every specimen of the insects in question 

 which has yet come beneath my notice. 



Under all cu-cumstances, I apprehend that the species which we are discussing 

 may be determined by then* limbs and prothorax, — the former of which are much 

 thicker in the II. Vnlcaniis than in the coufcrtns, whilst the latter is more excavated 

 behind (thus not only causing the edges to be more sinuated, but likewise the pos- 

 terior angles to be either subacute or right angles ; whereas in the more regularly 

 rounded and somewhat smaller and less convex prothorax of the H. confertus, 

 they are comparatively obtuse). This, I think, will generally enable us to discri- 

 minate even the intermediate, or outwardly approximating, examples ; but, where 

 the inquiry simply lies between the two in thcu- typical conditions, the immensely 

 greater bulk of the U. J'ulcanus (apart from the minor features enmncrated in the 

 diagnosis) wQl prevent any doubt from being entertained, Qxcn. lirimd facie, on the 

 subject. Their modes of life moreover are in a high degree dissimilar, — the con- 

 fertus being the only Madeiran Ilelops (unless I am mistaken) of subcortical pro- 



