2 THE VOYAGE OF H.M.S CHALLENGER. 
abruptly from the forehead, and is truncated anteriorly, the single aperture so formed 
looking upwards and forward (vide Pl. I. figs. 1-5). In the Oceanitidee (e.g., fig. 8) the 
aperture viewed from in front is nearly circular, and with scarcely any appearance of a 
median septum. In the Procellarian genera, on the other hand (fig. 9), the aperture is 
more oval and distinctly double, owing to the median septum (formed by the coalesced 
inner walls of the narial tubes) being much less deeply, in a lateral view, excavated 
anteriorly, and so appearing to a greater extent superficially. The other Procellariimee 
repeat this form of nostril, though the septum becomes much thicker, so that the nostrils 
open in them by two perfectly distinct apertures (vide fig. 7, where the nostrils of 
Bulweria are shown). They might thus be said to be “ platyrrhine,” in opposition to the 
“catarrhine ” Oceanitidee and other genera already mentioned. It is in Bulweria and 
Majaqueus perhaps, that the nasal septum is broadest and most superficial ; in Prion it 
is well developed ; in the remaining genera it is less near the external opening, but always 
quite evident. In the genus Puffinus the septum is also broad, but the narial tubes are 
so obliquely truncated that they hardly rise above the lateral outline of the beak ; their 
openings are ovals, with their longer axis vertical or (Puffinus obscurus) oblique inwards. 
In Pelecanoides the nasal tubes are short and swollen externally ; the septum is 
distinct, but not broad ; and the apertures, which are sinuated ovals directed antero- 
posteriorly, look almost vertically upwards, their lateral outline being nearly parallel with 
the axis of the upper jaw. 
In the Diomedeine the nasal tubes are quite 
separate from each other, lying just at the lower 
margin of the “ culminicorn.” They are usually 
described as tubes with a distinct circular complete 
aperture, but on looking at this carefully, there 
may be seen (vide fig. 1) in front and below this 
tubular opening a deep cavity leading backwards 
and continuous behind, over the edge of the 
Fic. 1.—Base of Beak of Diomedea exulans, to show &Pparent outer boundary of the aperture, with the 
the form and position of the nostril, general cavity of the tube, an infolding of the outer 
wall of the latter forming the apparent outer wall of the tubular aperture. 
The nasal tubes of the Petrels are formed, it may be observed, by the elongation of the 
cartilaginous walls of the nasal capsules. The upper and lower turbinal cartilages are well 
developed ; the alinasal turbinal cartilage, on the other hand, is represented only by a 
slight ingrowth from the internal nasal wall. Such, at least, is the condition of these 
parts in Majaqueus, the only form I have examined as regards these structures. 
The legs are always bare of feathers for some little distance above the tarsal joint, 
the metatarsal scutellation extending upwards over the joint some little way, but disappear- 
ing where the leg is covered by the feathers, and there replaced by simple skin. 
