In addition to those which we have been just discussing, there are other influences (equally independent of mere heat and cold) by which insect modifications may be brought about,--modifications moreover of that precise character which must be referred, in general terms, to the nature of the country and of the soil in which they severally obtain: a very few examples, however, in illustration of their action, must suffice for our present purpose. The _Tarus lineatus_, Schoenh., is slightly shorter in Madeira, as also somewhat darker on its head and prothoracic disk (and with its elytral striae less deeply impressed), than it is in Algeria and Spain. The Madeiran specimens of the _Aphodius nitidulus_, Fabr., are usually a little paler, and more distinctly punctulated, than their northern analogues; as are also, in the latter respect, those of the _Clypeaster pusillus_, Gyll. The _Scydmaenus Helferi_, Schaum, is permanently smaller in the Madeiran group than it is in Sicily; and I believe that the _Achenium Hartungii_, Heer, of those islands, is but a local state of the _A. depressum_, Grav., of Central Europe. The _Bembidium tabellatum_ and _Schmidtii_, Woll., may be in reality but geographical modifications of the _B. tibiale_ and _callosum_ of higher latitudes; and the _Malthodes Kiesenwetteri_, Woll., of the common European _M. brevicollis_. Calcareous deposits would appear, ever and anon, to have considerable efficacy in regulating the outward aspect of such species as are able to adapt themselves to different geological districts; and when in juxtaposition with the shore, their effects are often very conspicuous. The _Dromius arenicola_, Woll., is the Portosantan representative of the _D. obscuroguttatus_, Dufts.; and distinct as it is in colouring from that insect (as evinced both in Madeira proper and throughout Europe), I believe it to be in reality but a local condition of it, occasioned by a residence through a long series of ages on a calcareous soil. For the same reason perhaps (though assisted, in all probability, by the qualifying power of isolation), the _Hadrus illotus_, Woll., may be specifically identical with the Madeiran _H. cinerascens_. In like manner, the _Bembidium Atlanticum_, Woll., which in Madeira proper is frequently so dark that its elytral patches are sub-obsolete, and which is but seldom brightly arrayed in that island, assumes in Porto Santo (which is not only more calcareous than the central mass; but is strongly impregnated, as its streams and rills everywhere testify, with muriate of soda) a permanently paler hue,--being at times almost testaceous. Some districts seem to be more prolific in varieties, generally, than others. The neighbourhood of Ipswich, in our own country, has been cited by Mr. Curtis[29] as possessing this peculiarity; and I have remarked a similar tendency in certain parts of Ireland. The common _Haliplus obliquus_, indeed, of