THE AMPHIBOLY. 107 



other species the sparse plumage completely covers the whole hinder part of the back, passing 

 not only over the thighs, but even upon the tibiae. I found no such differences in the inferior 

 tract. Simple as far as the middle of the neck, and separated from the dorsal tract by a broad 

 lateral neck-space which reaches to the head, it divides at the middle of the neck into two limbs, 

 which pass on the breast in a converging direction, and here, after sending off a single row of 

 feathers to the axillary tract, form a parallel-sided, strong, and perfectly free outer branch, from 

 the extremity of which a hook is emitted only in M. varieffata, and even this is not continued 

 upon the arm, the hypopterum consisting only of semiplumes. The main stem, which is at first 

 narrowed, runs onward close beside the sternal keel, passes slightly divergently upon the belly, 

 and terminates somewhat laterally near to and in front of the anus. Besides these the axillary 

 tracts alone are noticeable as strong feather-bands. The wings are covered above by a dense 

 plumage, which reaches pretty nearly to the axillary tract, but is almost wanting beneath as far 

 as the rows of feathers on the anterior margin of the wing-membrane and those of the fore-arm. 

 On this inferior wing-space, as also at the upper end of the central inferior space, I found down- 

 feathers ; but these were wanting on all the other spaces, as well as between the contour-feathers. 

 The number of remiges is twenty-two or twenty-three, of which ten are inserted on the pinion. 

 The first three are graduated, and the fourth, fifth, and sixth are the longest. The long tail 

 always consists of ten feathers. 



B. With the stems of the inferior tract dilated, and no divergent outer branch, 

 a. Dorsal tract dilated on all sides, and sparsely feathered. 



The genus Colius, which was first declared to be allied to Corythaix by Burchell (' Travels in 

 Southern Africa,' vol. i, p. 214 [1822]) an opinion long since entertained by me, and recently 

 strengthened by anatomical investigation has a very remarkable arrangement of the feathers, and 

 can only be compared in this respect with Buceros. This relation may be recognised from the 

 representation of the pterylosis of Colius capensis given on PlateVI, figs. 10 and 11. In this species 

 and in C. striatus I found a general sparse plumage, the contour-feathers of which are distinguished 

 by their remarkably soft and thin tubes, and therefore do not everywhere project equally distinctly 

 through the skin. It is only in the region of the outer branch of the inferior tract, the occipital 

 portion of the dorsal tract, and the hinder part of the latter, that we find stronger feathers; and 

 those on the last-mentioned part form anteriorly two recognisable limbs, between which the 

 weaker plumage; of the interscapuliurn penetrates. Hence there remain on the body only the 

 following small downless spaces : 1, aright and left lateral neck-space reaching to the shoulder; 

 2, a likewise double but very narrow rump-space ; 3, a tolerably large, double axillary space ; 

 and, 4, a simple inferior space, in which the anal opening is situated, and which is entirely 

 confined to the hindmost portion of the ventral surface. To these may be added 5, a scarcely 

 perceptible, simple occipital space at the extremity of the occiput, resembling that of Trochilus 

 but much smaller. The species examined had nineteen remiges, of which ten were inserted on 

 the pinion. The first four are graduated, and the fifth is the longest. The number of rectrices, 

 which are strong and stiff, is ten ; but the two outermost are so small, and stand so far above, 

 almost over the two following, that they may easily be overlooked. 



