144 PTERYLOGRAPHY. 



starting from the knee-covert, in such a manner that a short continuation of the tract, which is to be 

 regarded as an outer branch, passes near the knee into the lateral space of the trunk, runs on over the 

 thigh, and soon afterwards terminates. The other, inner branch, which represents the main band, 

 then proceeds upon the belly, turns in a somewhat arcuated form outwards, dilates considerably 

 in the middle of the bow, and terminates near the anus. By this means the inferior tract 

 acquires nearly the appearance of that of the genera Hcematopus, Chionis, Dramas, Recurvirostra , 

 Thinocorus, &c., among the Scolapacince, departing chiefly from the type of these birds only in 

 having a much shorter outer branch, which is free only at its extremity. The dorsal tract is at first 

 broad, becomes narrower towards the middle of the neck, then expands to the shoulder, and 

 divides at that point, or from the middle of the scapulae, into two limbs. In most of the Tubi- 

 nares these limbs pass uninterruptedly into the posterior half of the dorsal tract ; and this circum- 

 stance forms their family character as distinguished from the Longipennes. In the present group 

 the posterior half of the dorsal tract encloses a longitudinal space as far as the caudal pit, dilates a 

 little outwardly upon the pelvis, and thus usually becomes united with the very oblique lumbar 

 tracts, and grows rather strong in the simple uropygial band, also covering the base of the oil- 

 gland. The latter is always of very remarkable size, and has a strong circlet of feathers on the 

 mamilla, but rarely more than two orifices. Diomedea, which possesses a greater number, also 

 differs in having the anterior part of the dorsal tract separated from the posterior simple part, and 

 presents several deviations from the type of the family, especially in the length of its wings and 

 some other characters. The same fact is likewise expressed in its very broad and strong axillary 

 tracts, and the comparatively small size of its hypopterum. 



1. Procellaria. The tract-formation in P.glanalis (PI. X, figs. 1 and 2) maybe regarded 

 as well representing of the general character the family, from which, however, some 

 species differ in particular points. It may be seen from the figures, that the inferior space 

 actually reaches to the angle of the throat, that the emargination in the inferior tract at the knee- 

 covert is moderately deep, that the ventral portion of this tract is but little widened, and that the 

 dorsal tract is connected posteriorly, where it becomes broad, with the lumbar tracts, which are 

 neither very strong, nor separated from the plumage of the tibial regions. In the wing I found 

 thirty-two remiges, of which ten are seated on the pinion, and the first is the longest. The tail 

 con tain s fourteen rectrices. The pterylosis in P. capensis is precisely similar ; but the notch in the 

 inferior tract near the knee is deeper, and the ventral portion broader. The number of remiges is 

 only thirty-one, but that of the rectrices is fourteen. P. giyantea exhibits no difference in the 

 inferior tract, except that it is broader, and the notch is consequently deeper in proportion. In the 

 dorsal tract, however, the anterior part can be clearly distinguished from the posterior by its 

 stronger and more densely feathered formation, although the two parts pass directly into one 

 another. The posterior part consists of two converging rows of strong contour-feathers, which 

 become parallel from the caudal pit, and form the simple uropygial band, but have scattered, 

 weaker contour-feathers beside them, by which they meet the biserial and rather strong, but short 

 lumbar tracts. The anterior part is comparatively more deeply cleft, and the spinal space reaches 

 the level of the shoulders. The number of remiges amounts to thirty-eight or forty, their 

 relative length continuing the same ; the number of rectrices is sixteen. In the large 

 oil-gland I think I detected several orifices in each half. P. pelagica is characterised by narrower 

 tract-bands, but has a dorsal tract of precisely the same form as in P. gigantea, except that the 

 scattered contour-feathers near the hinder part are wanting. In the wing I counted 



