THE CLASSIFICATION OF BIRDS 2? 



behind its articulation with the quadrate. The Anseres are aquin- 

 cubital, and have normal plantars, the spinal feather-tract is not 

 defined on the neck, they have a tufted oil-gland and holorhinal 

 nasals, the ca3ca are well developed, the hallux is elevated, small 

 (occasionally absent) and not united to the second digit by a web, 

 and there is no extraordinary development of the cnemial process 

 of the tibia. 



The Anseres comprise three well-marked families. The Ana- 

 tidce are the only birds except the Galli which have basipterygoid 

 processes placed as far forward as possible, The Palamedeidce * 

 are the only birds which have lost the uncinate processes of the 

 ribs. The Phcenicopteridoe differ from the other two families in 

 the Order in various other ways, of which the remarkable length 

 of their legs and the scutellation of the tarsus both in front and 

 at the back are the most conspicuous. 



The Anatidce may be regarded as cosmopolitan ; the PJmni- 

 copteridce as circumtropical and, to a limited extent, subtropical 

 also; whilst the Palamedeidce are confined to tropical and sub- 

 tropical South America. 



3. HERODIONES. 



The Herodiones possess many characters in common, though 

 the families which constitute them vary considerably from each 

 other, especially when the Jbididce have been added to the number. 

 This family differs from all the others in the Order in being 

 schizorhinal. In none of the families is the spinal feather- tract 

 defined on the neck, but there is considerable variation in their 

 pterylosis. Ihe Scopidce are peculiar in having lateral bare tracts 

 on the neck, but the spinal feather-tract is replaced by a spinal 

 bare tract. The Ardeidcc are peculiar in having an interclavicular 

 process within the angle of the furculum, and in having a large 

 powder-down patch on each side of the breast. The Ciconiidce 

 remain as the typical family, with no powder-down patches -f- on 



* It has been stated that Palamcdea cornuta is quincubital (Beddard and 

 Mitchell, " Proceedings of the Zoological Society," 1894, p. 536). I venture to 

 think that this is an error ; I have examined the relaxed wing of a specimen of 

 this species in the British Museum, and find an extra covert both above and below 

 between the fourth secondary and the one next it. 



t The wide distribution of powder-down patches is a remarkable instance of 

 the independent acquirement of a curious and apparently useless character. It is 

 not known that any strictly aquatic bird has any powder-down patches, but in 

 the Herodiones Balazniccps has one pair, Botaurus two, Ardea three, and Cancroma, 



