ACCIPITRES 485 



It is clear from the few characters the principal ones, 

 however given in the above list that the Cathartidae are 

 more aberrant (considering the Falconidee to be the typical 

 birds of prey) than are the Serpentariidaa ; for the 

 Cathartidse diverge in all eight characters from the Fal- 

 conidae, while the secretary vulture only diverges in three. 

 What reason is there, it might be asked, to retain the 

 American vultures within this order at all, particularly 

 if the owls are to be as I think they should excluded ? 

 The only group which has the distinctive characters of the 

 Cathartidae (besides, of course, the present group) is that of 

 Herodiones. There only do we find birds with ambiens and 

 expansor secundariorum, without biceps slip, holorhinal, and 

 with rudimentary or absent cseca. The Steganopodes also 

 are not far off. It really conies to the beak and claws, the 

 ceroma, and to the presence of various structures (e.g. the 

 peculiar palate, the basipterygoid processes) which forbid 

 their association with the Herodiones. The several groups 

 are not far off, but on the whole the American vultures are 

 more like the remaining birds of prey than like the stork 

 tribe (see also under the discussion of the affinities of the 

 Grues, p. 882). 



TINAMI 



Definition. Oil gland tufted. Q,uintocubital. Muscle formula of 

 thigh, ABXY"+. Expansor secundariorum present. Biceps 

 slip absent. Both carotids present. Large caeca and crop. Skull 

 dromseognathous. Tail short without ploughshare bones. Bones 

 of pelvis free distally. 



The tinamous are purely South American birds, of which 

 in his recent catalogue Count SALVADOEI allows nine 

 genera. 



The tinamous have a tufted oil gland, but the tuft is often 

 very minute, and in Calodromas elegans consists of only four 

 feathers, two larger and two smaller, the larger ones being 

 uppermost. 



I take my account of the pterylosis of the tinamous from 



