418 Coleopterological Notices. 



subserves a different purpose and is not apparently subject to change 

 from any of those conditions which affect the hirsute covering of 

 the warm-blooded animals. This is true at any rate of those hairs 

 which are termed tactile and which are very plainly of functional 

 value, but may possibly not apply so rigidly to other forms of 

 vestiture which, for want of any other name, we call ornamental ; 

 the degree of structural variation even in these hairs or scales is, 

 however, comparatively slight as far as my experience has led me. 

 It is highly probable that this ordinary or ornamental pubescence 

 in insects is simply a degenerative modification of hairs, which in 

 their original state were tactile and sensory, but which have become 

 functionless through disuse and at the same time more or less changed 

 in structure. 



3 — Another variable function is the degree of dilatation of the 

 anterior and intermediate tarsi of the male and the vestiture of their 

 under surface, these organs being, — in partial contradiction of all 

 generic diagnoses which have been heretofore published, — occasion- 

 ally completely undilated and spinose beneath, as for example in 

 brevicollis. In the more widely dilated tarsus the under surface is 

 always very densely spongy-pubescent. The two groups into which 

 I have divided the majority of our species, depending upon the 

 amount of dilatation, are of course unnatural, and it may occasion- 

 ally be difficult to distinguish the dividing line between them, the 

 more strongly dilated tarsi of the second group as in arenarius, 

 being approached by the more feebly dilated members of the first 

 group as in longulus. The only definite criterion which can be 

 n-iven, is that in the feebly dilated tarsus the second and third joints 

 are never more than very slightly wider than the apex of the fifth. 



The impression of the fifth segment is not strictly sexual, being 

 often visible in the female and is always variable; the impression 

 of the abdomen toward base is, however, peculiar to the male and 

 generally quite constant. 



pointed or truncate spicules, usually aggregated in clusters, third a system of 

 very sparsely placed long white erect setae, and finally, each puncture of the 

 strise has a peculiar minute seta which is unlike any other part of the vesti- 

 ture. In addition to this the scales of the first system are, on the under 

 surface, often most beautifully and minutely fimbriate or plumose around the 

 circumference. To fathom the mysterious processes of nature which have 

 resulted in such complexity, or to explain how these four systems act in 

 mutual relationship, will most undoubtedly forever be beyond the pale of our 

 feeble understanding — we can only wonder. 



