To ordinary observers a Swift appears so much like a Swallow, that the only difference discernible by them is a difference of colour. To the inquiring naturalist, however, a much more important distinction presents itself in the peculiar and remarkable anatomy of the former bird. Not only has it a greater extent of wing, moved by larger and more powerful muscles, but the structure of the foot is curiously adapted for climbing within the narrow crevices which are usually selected as nesting-places. In the Swallow and other _Hirundines_ the toes are long and slender—three in front and one behind in the same plane, as is usual with insessorial birds. In the Swift we find the toes short and stout, and all four directed forwards; the least toe (which should be the hind one) consisting of a single bone, and the other three of only two bones apiece—a peculiar construction, but well adapted for the purposes for which the feet are employed. This singularity of structure has induced naturalists to consider the Swifts (for there are several species) generically distinct from the Swallows; and the former, therefore, are now placed by common consent in the genus _Cypselus_, a name adopted from Aristotle, and suggested by Illiger, as indicating the bird’s habit of hiding its nest in a hole. The remarks which have been made upon food in the case of the Swallows, apply equally in the case of the Swifts. The latter have so frequently been observed in localities presenting very different species of insects, and sweeping in the summer evenings through the midst of little congregated parties of various kinds, that there is little doubt that the nature of the food differs very considerably. In corroboration of this it has been shown that anglers have repeatedly captured these birds with artificial trout-flies of very different appearance.[76] Isaak Walton informs us that Swifts were in his time taken in Italy with rod and line; and, according to Washington Irving, one of the sports of the Alhambra was angling for swallows from its lofty towers.[77] There are several species of Swifts distributed throughout the world, but only two visit the British Islands, and of these one is but a rare and accidental visitant.