It is not surprising that ornithologists, who are so frequently compelled to form their ideas of natural divisions from mere skins, should be entirely unacquainted with the group, of which this genus is probably the type. But it is strange that the full and accurate information concerning it, which has long ago been furnished by Azara, should have been so utterly neglected. In the views which we have taken of the affinities of these birds, we consider they present a point of junction with the Saxicolæ; passing on one side into the genuine Flycatchers of America, (_Tyrannula_ Sw.) and on the other into the typical Todies. The contents however of this group, we are but partially acquainted with. It will comprise _Nengetus_, Sw. _Alecturus_, Vieil, and several other forms now widely scattered in the newest systems, together with one or two others not yet defined, which we have only seen in the Paris Museum. Since the above was printed, we find the name of _Xolmus_ has just been proposed for this genus by M. Boié, he not being of course aware that this, and some of his other groups, were published by us three years ago. * * * * * * [Illustration: MACROPTERYX _longipennis_. _Long winged crested Swift._] MACROPTERYX longipennis. _Javanese crested Swallow._ ---- Family Hirundinidæ. GENERIC CHARACTER. _Bill_ (_fig. 1.2._) small, entire, base depressed and straight, the outer half of the culmen suddenly curved; lower mandible straight, nostrils large, oblong: _Tarsi_ short, without scales; anterior toes of nearly equal length; (_fig. 3.4._) claws strong; hinder toe long, not versatile, the claw very short and thick. _Nob._ ---- SPECIFIC CHARACTER. _Above obscure glossy green; throat, breast, and lower part of the back light grey; belly, spot on the scapulars, and line over the eye, white; ears rufous; front with an incumbent crest._ Hirundo Klecho, Horsfield, Linn. Trans, xiii. p. 143, female? Cypselus longipennis. Pl. Col. Pl. 83, f. 1? ---- To Dr. Horsfield, one of the most successful and scientific investigators of Oriental Zoology, we are indebted for the first discovery, in Java, of this charming bird. Of its economy nothing is as yet known; but the uncommon length of its wings, indicate its possessing the utmost rapidity of flight. Another, and a much larger species, is among the Ornithological treasures discovered in the Eastern Archipelago by my estimable friend M. Lesson, and which he has already communicated to the public. A third is the _Cypselus Comatus_, of M. M. Temminck and Laugier. The peculiar structure of these birds oblige us to consider them as forming a natural group, intermediate between the typical Swifts, and the Swallows. To the first they are allied by their strong scansorial feet; to the latter by the length and fixed position of the hind toe, and the depression of the bill.