526 INSECTA MADERENSIA. 



centrally-thickened antennae, and invarialjly sluggish movements, give them a 

 character moreover essentially their own ; whilst the curious power which they 

 possess of emitting an oily fluid from their limbs, when alarmed, and which has 

 gained for them the popular name of " oil-beetles," will not tend to diminish their 

 general singularity. The structm-c of theii* tarsi, also, is exceedingly strange, — 

 since not only are the claws so completely bifid throughout their entire length as 

 in fact to constitute fom% but what appear to be the ordinary tibial spurs are, in 

 reality, of an organization altogether distinct, being articulated on, by means of a 

 strong membrane, to the basal joint of the foot. I have not seen this peculiarity 

 elsewhere alluded to ; but that it truly exists I have satisfied myself by the 

 destruction of a vast number of specimens, — observing, in every instance, that on 

 pulling off the tarsi (of each of the legs) the calcaria came away with them. I 

 conclude therefore that all the spines are capable of motion, since they are un- 

 questionably separate from the tibiae, and in fact (as my experiment proves) far 

 less firmly attached to it than to the foot. In every case indeed they required to 

 1)0 actually cut from the tarsus (even after the force necessarily exerted in tearing 

 it off) before the latter was unencumbered for examination. As regards the 

 processes themselves, the four anterior pair are of sunilar length, whilst the two 

 hinder ones (as in many of the kindred genera of the present family) are unequal, 

 — one of them being small, and the other greatly developed and flattened out (in 

 shape more or less hastate, or cultriform, being obliquely truncated at its tip). In 

 ZuiiU/s the same relative proportions obtain, but there the spurs would seem to be 

 fixed*, — or, at any rate, to be so intimately connected with the tibiae (although 



* Perhaps indeed the larger of these two hinder spurs iu the whole of these immediate genera (where 

 the struetiiro exists) can never be said to be positively fixed, siuee its unusual magnitude and peculiar form 

 would seem to imply tliat it was appropriated to some special purpose, wliere a certain amoiuit of play is 

 ill aU probability indispensable. Analogy moreover with the single immensely-developed process at the 

 apex of the male ybre-tibia; of Cantharis (which almost exactly resembles those in question, and the 

 uses of which are sufficiently obvious) woidd have led us even a priori to imagine that these now under 

 discussion woidd be found, in like mauuer, to be capable of motion : and hence, when wo speak of the 

 calcaria as (on the whole) "steadfast" or "moveable," I am inclined to suspect that these expanded 

 posterior ones (as belonging ahcm/s to the latter class) should be considered as excluded from our defini- 

 tion. Meanwhile, in eases where lotJi at any rate are not free, it is far from uulikelj' (since they appear 

 to be connected, and must needs therefore, if at all, come away together) that the stationary one may tend 

 to increase the attachment (to the tibia) of the other, and that so (though requiring a proportionably 

 greater force to efieot their removal) it may be possible to pull the tarsus out of its socket icitliouf 

 ca\ising the dislocation of tlie spines as in Meloi'', — where the whole of them seem (as I assiune from the 

 very fact of their universal annexation to the foot, and from the elasticity of the joining medium) to be 

 moveable. How far this cultriform appendage (for we can scarcely call it a spur, at least in the sense 

 connnoiily understood by that term) may be tlie exponent of the missing joint in tlie liiuder feet of these 

 rieteromerous groups, I do not venture to speculate, nor would I attempt to throw light on a fact thus 

 physiologically important from small and imperfect data, gleaned from the observation of a single circum- 

 stance : yet its structiu-e is imquestionably suggestive of more than a mere modijication of the ordinary 

 calcaria of the Coleoptera ; and, however luilikely we may be to extract an iota of truth from the 

 inquiry, yet I believe it to be one which is not altogether so absurd as at first sight it might perchance 

 appear. 



