THE GALL1NACE.E. Ill 



i 



beginning of the neck ; 2, the absence of the superior wing-space ; 3, the coalescence of the 

 lumbar tracts with the hinder part of the dorsal tract ; and, 4, the union of the latter tract with 

 the plumage of the tibia. On the other hand, the form and structure of the anterior part of the 

 dorsal tract is exactly as in the Pigeons, whilst the hinder part certainly has the same general 

 constitution, but is much more dilated, and extends far more deeply between the arms of the 

 scapular fork. To this may be added, that in P. coronatus and P. exustus the narrow spinal space is 

 entirely wanting, but is distinctly present in P. setarius. In all these I found from twenty- 

 seven to twenty-eight remiges, of which the ten belonging to the pinion are all strikingly 

 graduated, so that the first is the longest ; the secondaries again increase somewhat in length, 

 but the longest of them is still scarcely half so long as the first primary. The tail always 

 contains sixteen rectrices. Lastly, the Sand Grouse are distinguished from the Pigeons by the 

 presence on the contour-feathers of an after-shaft (which, however, is but small) ; from the 

 Gallinaceous Birds by the oil-gland being perfectly naked, even at the tip ; and from both these 

 groups by the perceptible, although weak, downy coating of the spaces. 



CHAPTER V. 

 GALLINACEOUS BIRDS Gallinaceae. 



FEW families of equal extent have so concordant a pterylosis as that to the consideration of 

 which we now turn, and, with the exception of the still more uniform Passerinse, scarcely any 

 group of birds of this rank can vie with it in the definiteness of its general type. Hence a 

 general and accurate representation of it may be given with peculiar facility and completeness. 



The contour-feathers have a considerable but only downy after-shaft, which is attached to the 

 end of the very short and delicate quill, and is but weak in comparison to the very strong stem of 

 the main shaft. The latter also bears far more downy than pennaceous barbs, and is characterised 

 in the dorsal feathers of many genera (for example, Polyplectron, Argus, Cryptonyx, Penelope, 

 Crax, Crypturus) by the enormous width of that portion of its extent on which the downy 

 barbs are seated (see Plate I, fig. 1). True down-feathers are rare, and are entirely wanting 

 among the contour-feathers ; they stand singly here and there upon the spaces, most abundantly 

 on the lateral spaces of the trunk, and become converted into semiplumes in proportion as they 

 approach the contour-feather tracts. I have also observed down-feathers in the space between 

 the outer branch and the main band of the inferior tract, as also on the inferior space in the 

 jugular region immediately over the furcula; on the contrary, the lateral neck-space, which 

 extends nearly to the head, is always naked. I have found powder-down feathers only in one 

 genus, namely Crypturus. Here they form the border of the greatly elongated saddle of 

 the dorsal tract, and partially penetrate between its outermost contour-feathers. 



The tracts themselves are always very definitely bounded, but by no means very broad, 



