the present day, by _human_ agencies from the mountain-slopes; for, since the cutting of faggots is one of the few sources of livelihood to a large proportion of the poor of Funchal, numerous insects of subcortical and lichen-infesting tendencies are subject to be naturalized (provided they can adapt themselves to the change) in altitudes lower than their normal ones: so that there are many chances, even _a priori_, in favour of the _T. Lowei_ having overspread, whether by natural or artificial means, a wider area than its congeners. I believe that there is no such thing as a _Tarphius_ in the Canarian Group: nevertheless, singularly enough, a representative, which is more akin to the _T. Lowei_ than to any other hitherto discovered (and which was imagined until lately to have been the sole exponent of the genus), namely, the _T. gibbulus_, Germ., occurs in Sicily. From which data we arrive at this significant fact: that, whilst Madeira proper is, without doubt, the original centre of the _Tarphii_, two species (one of which is, likewise, Madeiran) are found in Porto Santo, to the north-east of it; whilst a third makes its appearance in an island of the Mediterranean. The genus _Acalles_ presents a nucleus of species in the Canaries, moulded on a very large pattern. A closely allied member, the _A. Neptunus_, Woll. (which may perhaps be in reality but an insular modification of the _A. argillosus_, Schoen., from Teneriffe), has been detected on the rocks of the Salvages, to the north of them; whilst on the Dezerta Grande, one of the most southern stations of the Madeiran Group, we have a third, which displays far more in common with the Canarian type than it does with that which obtains in Madeira proper;--which last is gradually, in its turn, merged into the ordinary European form. The genus _Pecteropus_, Woll., is another instance in point. I possess three or four species from the Grand Canary, Fuertaventura, and Teneriffe; and I believe it will be found, on inquiry, to attain its maximum in that cluster. Unlike the others, however, which we have just cited, it is powerfully winged; and we should consequently expect to trace the evidences of its northward progression with comparative perspicuity. Can we therefore do so? Yes: in Madeira proper it has two representatives, and in Porto Santo (to the north of it) one. And so with _Xenostrongylus_, Woll. (which is likewise winged), we have two species, at least, in the Canaries; one in the Madeiras; and a third, unless I am mistaken, in Sicily. The genus _Ditylus_ is shadowed forth in the Canary Islands by two or three singular representatives of a pallid, testaceous hue; and, although the group is entirely absent in Madeira, a species (the _D. fulvus_, Woll.) is found on the 'Great Piton' of the Salvages, so nearly resembling, except in its smaller size, one of those from the Canaries that I think it far from improbable that it is a fixed insular state of that insect.