122 PTERYLOGRAPHY. 



inferior wing-space, but also pretty clearly on the cervical portion of the dorsal space. These 

 down-feathers, as also the lowest downy barbs of the contour-feathers, are remarkable for their very 

 intense rosy red colour, in which they differ greatly from the grey or white down of all other 

 birds. When exposed to the light they lose their colour, and are therefore paler in proportion 

 as they are high up on the feather. The tracts are remarkable in many respects. The dorsal 

 tract is divided high up on the back of the neck, and continues, uniformly becoming stronger, as 

 far as the extremity of the shoulder-blades. Here, immediately on the inner margin of each 

 limb, commences the much weaker hinder part, which then encloses a much narrower space and 

 widens exteriorly. Hence the strong lumbar tracts, which extend to the knee, nearly come in 

 contact with the dorsal tract. From the caudal pit onwards the dorsal tract is simple, and, 

 combining with the lumbar tracts, clothes the hinder pelvic region and the tail in the form of an 

 uninterrupted plumage, in which the oil-gland would be situated if it were present ; it is, however* 

 entirely wanting. The inferior tract is undivided, at least to the middle of the neck (in 0. tetrax), 

 or even to its extremity (in 0. tarda), and is connected laterally with the dorsal tract, so that the 

 lateral neck-space is absent with the exception of a small rudiment at the base, immediately in 

 front of the shoulder. In 0. tetrax each limb becomes somewhat broader as it passes on the 

 breast, and emits at this point a branch equal to the main stem and parallel and closely approxi- 

 mating to it, which terminates before reaching the end of the musculus pectoralis major, whilst the 

 main stem of the tract passes on to the belly, where it is greatly bent outwards, and runs on to 

 the anus, towards which it turns in a curve. The remarkably broad inferior space formed by 

 this course of the inferior tract is neither naked nor clothed only with down, but bears six rows 

 of contour-feathers distributed at equal distances upon the surface of the space ; these, however, 

 are shorter than the tract-bands, and terminate at the middle of the belly, but reach anteriorly to 

 the end of the division of the two bands. The inferior tract in 0. tarda is differently formed 

 (Plate VIII, fig. 1). In this species it only divides behind the furcula, and emits no outer branch, 

 but is strongly dilated on the fore part of the breast, although the outer branch is indicated by a 

 sudden narrowing at the end of the pectoralis major, and by the greater strength of the feathers at 

 this part. Instead of the six rows of contour-feathers there are, in the still broader inferior space, 

 two inner tract-bands, which are at first four, soon afterwards three, and from the end of the 

 sternum only two feathers in width, continuing thus in a straight line to the anus, where they 

 coalesce with the outer main bands. The axillary tracts are broad and strong, scarcely separated 

 by a narrow space from the homogeneous plumage of the wings ; beneath there is, instead of 

 them, a general space on the wing, in which, on the humerus, the feathers of the hypopterum 

 proceeding from the breast are situated. The number of remiges is thirty-two in 0. tarda, 

 thirty in 0. telrax, of which ten are seated on the pinion ; the first of these is remarkably and 

 the second slightly abbreviated; the third and fourth are the longest. In the tail I counted 

 twenty feathers in both species. With the exception of 0. tarda and 0. tetrax, I have not been 

 able to examine any species pterylographically. 1 



The exact determination of the natural affinities, and consequently of the systematic position, of 

 the Bustards, is a very difficult task. In the structure of the skeleton, especially in the form of the 

 sternum and furcula, Otis agrees perfectly with the Snipes, especially with Numenius ; in the structure 

 of the skull it most closely approaches (Edicnemus, but diverges very distinctly from the type of the 

 Limicola in some respects, for example, in the position of the small nasal glands in the orbit. 



