The _M. leucurus_ is a noisy bird, and utters several harsh cries; of which, one is so like that of the English rook, that the sealers always call it by this name. It is a curious circumstance, as shewing how, in allied species, small details of habit accompany similar structure, that these hawks throw their heads upwards and backwards, in the same strange manner, as the Carranchas (the Tharu of Molina) have been described to do. The _M. leucurus_, builds on the rocky cliffs of the sea-coast, but (as I was informed) only on the small outlying islets, and never on the two main islands: this is an odd precaution for so fearless a bird. 4. MILVAGO ALBOGULARIS. PLATE I. Polyborus, (Phalcobænus) albogularis, _Gould_, Proceedings of Zoolog. Soc. Part V. (Jan. 1837.) p. 9. _M. Fæm. fuscescenti-niger, marginibus plumarum inter scapulas fulvis; primariis secundariisque albo ad apicem notatis; gulá, pectore, corporeque subtùs albis; lateribus fusco sparsis; rostro livido, lineis nigris ornato; cerâ tarsisque flavis._ Long. tot. 20 unc. ½ rostri, 1⅝; alæ, 15¾; caudæ, 9; tarsi, 3. _Description of female specimen, believed to be applicable to both sexes._ COLOUR.—Head, back, upper wing coverts pitch black, passing into liver brown; feathers on back of neck and shoulders terminating in a yellowish brown tip, of which tint the external portion of the primaries, and nearly the whole of the tertiaries partake. Tail liver brown, with a terminal white band nearly one inch broad; base of the tectrices white, irregularly marked with brown: upper tail coverts white. All the feathers of the wing tipped with white, their bases irregularly barred with transverse marks of brown and white. _Under surface._—Chin, throat, breast, belly, thighs, under tail-coverts, under lining of wings, and edge of shoulders perfectly white. On the flanks, however, there are some brown feathers irregularly interspersed; and on the lower part of the breast, most of the feathers show a most obscure margin of pale brown. Bill horn colour. Cere and tarsi yellow. [Illustration: _Birds. Pl. 1._ _Milvago albogularis_ ]