This is the _Hirundo urbica_ of naturalists, the latter term coming from the Latin _urbs_--a city. Its plumage is of a more decided purple tint than the Common Swallow, from which it is also distinguished by the absence of chestnut brown on the forehead, throat, and under parts, which in this species are pure white. In its habits the Martin closely resembles its congeners, than which it is, perhaps, even more a house and city bird; hence its specific name. It reaches our island generally a few days later than the Swallow, and departs at about the same time. The eggs of this bird are four or five in number, of a longish oval shape, smooth, and perfectly white. The nest, which is composed of mud, so cemented and tempered that it will adhere even to glass, is lined with hay or feathers. Gilbert White, in his "Natural History of Selborne,"--a delightful book which all young naturalists should read, says that there are generally young birds in the nest up to Michaelmas, there being two broods, and sometimes even three, in the year; the first brood are generally ready to fly by the latter end of May, and the second early in August: the period of incubation is thirteen days. SWIFT. COMMON, OR BLACK SWIFT. BLACK, OR SCREECH MARTIN. SWIFT-SWALLOW. DEVELING. SCREECH. SCREAMER. SQUEALER. CRAN. MARTIN DU, OF THE ANCIENT BRITISH. FIGURE 18. Like the rest of our Swallows, this is a migratory bird, and it remains with us a shorter time than most of the others, generally arriving in May, and departing in August. Its scientific name is _Hirundo apus_, meaning a Swallow without a foot, derived no doubt from the small size of the feet, and the little use it seems to make of them, being almost constantly in the air, where its evolutions are peculiarly rapid and graceful, even for one of its family. The rapidity with which it skims and dashes along, wheeling and turning in the most sudden manner, is truly marvellous; so great is the force of its forward impetus, that it has been known to kill itself by dashing against a wall; it has been estimated that Wild Ducks fly ninety miles an hour, and Swallows rather more, but the Swift above two hundred miles an hour; this may possibly be an exaggeration, but if we make a large allowance, say one half, the rate of progress is something astounding. The note of the Swift is a harsh scream, hence several of the common names by which it is known; it is generally uttered while pursuing its insect prey on the wing, and may be considered as an exclamation of triumph or delight, as much as to say,--"Ha, ha, I have caught you!"