There are other examples which might be quoted in support of my theory,--that isolation, when involving a sufficient period of time, has a direct tendency either to diminish the stature of the insect tribes, or else to neutralize their power of flight; but that, in the latter case, the creatures, when thus despoiled of a function, do, on the contrary (instead of deteriorating in size), often receive a compensation for their loss by an actual _increase_ in their bulk. The common _Bradycellus fulvus_, Mshm, is another instance in point. From its occurrence in the almost inaccessible districts of the Madeiran group, far removed from cultivation, I am inclined to refer its entry into this southern region to that remote period when a connective land offered a natural passage to wanderers from the north. Hence our first stipulation, that of _sufficient time_, is satisfied; and what is the result? The insect is a trifle more robust than its ordinary European representatives, and it is _invariably apterous_. The _Calathus fuscus_, Fabr., is also, as is clear from its special attachment to the mountain tops, strictly indigenous in Madeira (that is to say, it must have arrived there during the migratory epoch); and the consequence is, that, although usually winged in our own country, it is permanently subapterous in that island. I think it far from unlikely that the _Dromius negrita_, Woll., may be the ultimate phasis (from isolation) of the common _D. glabratus_, Dufts.,--from which it may be distinguished by its somewhat larger bulk, more robust head and prothorax, and by the obsoleteness of its wings. True it is, that the latter species flourishes alongside it in Madeira; but, like the _Vanessa Atalanta_ (when considered with respect to the _V. Callirhoe_), may it not be of more recent importation from the European continent, and as yet in a transition state?--an idea which the _smallness_ of its wing, as compared with those of its British analogues, would seem rather to corroborate. But, if this slight increase of stature would appear generally to accompany that gradual extinction of the powers of flight which isolation is apt to induce, it follows, on the other hand (as indeed I have lately intimated), that where wings are so essential to the continuance of a species that they cannot, without its positive destruction, be taken from it, the _primary_ effect of isolation,--namely a diminution of bulk,--will for the most part happen instead. As this fact, however, has been already commented upon, we will not discuss it afresh.