Since writing the above, I find this bird is figured and described in a beautiful work commenced by Lewin on the birds of New Holland, which Mr. Brown, the learned possessor of the Banksian library, pointed out to me. I believe but a few copies are known. Lewin observes, "it inhabits heads of rivers, visiting dead trees, from the branches of which it darts on its prey in the water beneath, and is sometimes completely immersed by the velocity of its descent." Dr. Latham has very well described it, but quite overlooked the construction of the feet. * * * * * Pl. 27 [Illustration] HALCYON collaris. _Collared Crabeater._ * * * * * GENERIC CHARACTER. _Rostrum longissimum, rectum, validum, ad basin latius quam altius, lateribus tetragonis; mandibula superiore rectissima, ad basin rotundata; inferiore carinata, recurvata, margine superioris inferiorem obtegente. Nares basales, membrana tectae, apertura nuda, lineari obliqua. Cauda plerumque mediocris. Pedes gressorii, digito antico interiore minimo aut nullo._ Typus Genericus _Alcedo Senegalensis_. Linn. Bill very long, straight, thick, the base broader than high; the sides tetragonal; upper mandible very straight, the base rounded; under mandible beneath carinated and recurved, the margins covered by those of the upper. Nostrils basal, covered by a membrane, the aperture naked, linear and oblique. Tail mostly moderate. Feet gressorial: interior fore-toe small or wanting. Generic Type _Crabeating Kingsfisher_. Latham. * * * * * SPECIFIC CHARACTER. _H. viridi-caerulea; corpore subtus, lunulaque cerviculi albis._ Greenish-blue. Body beneath and nuchal collar white. Alcedo collaris. _Latham Index Ornith._ i. 250. Sacred Kingsfisher, _Var._ D. _Latham Syn._ ii. _p._ 623. Collared Kingsfisher. _Gen. Zool._ viii. i. _p._ 80. * * * * * Referring to the observations we have already made on Kingsfishers generally, it will be only necessary to observe, that the species now formed into the genus _Halcyon_ appear entirely excluded from the American continent: their bills are much stronger, thicker, and more rounded than the genuine Kingsfishers, and the under mandible beneath invariably carinated and curving upwards. One of them (the _Alcedo Senegalensis_ of Latham) is known to feed on crabs, the breaking and disjointing of which this structure seems admirably calculated to accomplish; and although some authors mention insects also as their food, I apprehend it is only in the absence of other larger prey more suited to the construction of their bills.