XXIV INTRODUCTORY REMARKS. 



tions would imply, is altogether so difficult, and concerning which 

 therefore we have yet so much to learn, as Acalles ; and I must conse- 

 quently be content to leave some of the problems which it suggests 

 unsolved, and will merely refer to certain remarks which I have 

 made on that subject at p. 270 of this work*. 



Scarcely less numerous than Acalles in reality perhaps more so 

 (for there must be many still undetected) are the species of that 

 singular genus Tarphius, which (so far as yet brought to light) 

 amount to 34. On the whole, indeed, I should look upon the Tarphii 

 as emphatically the most characteristic of all the Coleoptera in this 

 widely scattered archipelago, at any rate of those which constitute an 

 extensive generic assemblage ; for not only are they (in every instance) 

 unmistakeably endemic, and apparently adapted to the particular 

 regions which contain them, but likewise so sedentary and phleg- 

 matic in their modes of life, and so circumscribed in their several 

 areas of diffusion, that it is impossible to resist an inquiry as to what 

 the particular offices may have been which they were originally de- 

 stined to fulfil in the economy of those remote and elevated sylvan 

 districts which they would seem (almost solely) to inhabit. Though 

 not absolutely peculiar to the islands for a single representative 

 occurs in the south of Europe, and a second has lately been found 

 in Algeria there can be little doubt that the Atlantic province of 

 which these Groups are now the detached parts was the great pri- 

 meval centre whence the Tarphii emanated, and to which, in point 

 of fact, they are even still principally confined. 



Helops likewise is very largely expressed, and perhaps also more 

 difficult to investigate satisfactorily than even Acalles. As in the 

 case of the latter, it seems to be preeminently " sportive ; " so that 

 we are often left in doubt as to whether forms which appear, in par- 

 ticular districts and elevations, to be tolerably well-defined are more 

 in reality than local states of species which are plastic and widely 

 spread. Still I believe that there are but few (not more than about 

 five) of those here enumerated which will be likely to have their 

 specific claims called in question ; and since it is most improbable 

 that all the Atlantic representatives have yet been brought to light, 



* Although often self-evident, these " representative " species (not only in 

 Acalles, but likewise in various genera) are frequently so doubtful that I have 

 thought it safer not to attempt to indicate them universally in my Tabular Cata- 

 logue, lest too much stress should be laid on the subject, and my conclusions 

 should consequently be relied upon too confidently by those who are not disposed 

 to take the trouble to examine for themselves. I have always, however, alluded 

 to them, where the evidence seemed to warrant it, in the body of the work. 



