Dr. Latham first instituted this genus, of which two species were then known; M. Le Vaillant discovered another in Africa; and I am happy in now adding a fourth from the same country, in the possession of Mr. Leadbeater. No ornithologist has paid greater attention both to the natural affinities, and to the illustration of the genera allied with these birds, than Professor Temminck; and I therefore feel pleasure in naming this bird in honour of that excellent ornithologist, from whom whenever I have differed, it has been from the sole wish of eliciting truth. Total length from the bill to the tail eight inches; bill one inch from the gape, and half from the end of the nostrils; the colours of the bird are best seen in the figure; the middle of the body, and the quill feathers, deep black; legs three inches from the naked thigh to the tip of the middle toe, the claw of which is serrated internally; tail round; the middle feathers not spotted; the two next with a black dot near the tip, which, in the next pair, is further broken into two white dots; the outer pair white. These birds inhabit the arid tracts of Africa, at a distance from the sea, and run amazingly swift. One species has occasionally visited England. * * * * * Pl. 107 [Illustration] TROCHILUS ensipennis, _Blue Sickle-winged Humming Bird._ * * * * * GENERIC CHARACTER.--See Pl. 82. * * * * * SPECIFIC CHARACTER. _T. (div. curvirostrae) aureo-viridis, mento juguloque caeruleo-violaceis; rectricibus paribus; alis falcatis, remigum primorum scapis dilatato-compressis._ Curved-bill Humming Bird, golden green; chin and fore part of the throat violet-blue; tail even; wings falcated, greater quills with the shafts dilated and compressed. * * * * * I have already offered some observations on the remarkable construction in the wings of _T. falcatus_, figured at pl. 83; and the bird now before us is another unrecorded species, possessing exactly the same formation. I was at first inclined to believe this bird was the male of the _T. latipennis_, (or _l'Oiseau Mouche a larges tuyaux_ of Buffon), from the under plumage in that species being uniform grey, a common indication of the female Humming Birds; but a further comparison of the two has proved this supposition to be erroneous. They differ, not only in colour, but in their bills; in that of _T. latipennis_, the curvature is so slight, that it may be almost called straight; whereas in this, the curve is very apparent. I have little doubt future observations will show, that these singular quill-feathers, now known to exist in three species of this family, are peculiar only to the male birds.