STEGANOPODES: TOTIPALMATE BIRDS. 
719 
observed among birds. It is represented by six genera, all North American, each the type of 
a family. 
The nature is altricial. The eggs are very few, frequently only one, usually if not always 
plain-colored, and encrusted with a peculiar white chalky substance ; they are deposited in a 
rude bulky nest on the ground, on rocky ledges, or on low trees and bushes in the vicinity of 
water. The dietetic regimen is exclusively carnivorous, the food being chiefly fish, sometimes 
pursued under water, sometimes plunged after, sometimes scooped up. In accordance with 
this, we find the alimentary canal to consist of a capacious distensible oesophagus not develop- 
ing a special crop, a large proventriculus with, numerous solvent glands, a small and very 
moderately muscular gizzard, rather long and slender intestines, with small coeca, if any, and 
an ample globular cloaca. The tongue is extremely small, a mere knob-like rudiment (as in 
the piscivorous kingfishers). The characteristic gular pouch varies greatly in development. 
The condition of the external nostrils is a curious and unexplained feature ; they appear to be 
open at first, and in some species, like the tropic-bird, they remain so ; but they are generally 
completely obliterated in the adult state. There are probably no intrinsic syringeal muscles 
in any birds of this order. But the most notable fact in connection with the respiratory system 
is the extraordinary pneumaticity of the body, which reaches its height in the pelicans and 
gannets. The interior air receptacles are of an ordinary character, but the anterior of these 
cells are more subdivided than usual ; from them, the air gets under the skin through the 
axillary cavities, and diffuses over the entire pectoral and ventral regions, in two large parallel 
inter-communicating cells on each side, over which the skin does not fit close to the body, but 
hangs loosely. It is further remarkable that the skin itself does not form a wall of these 
cavities, a very delicate membrane being stretched from the inwardly projecting bases of the 
contour-feathers. Thus there is yet another, although a very shallow, interval between this 
membrane arid the skin, this also containing air, admitted from the larger spaces by numerous 
minute orifices close to the roots of the feathers. This subcutaneous areolar tissue is that 
which, in ordinary birds and mammals, holds the deposit of fat, no trace of which substance 
is found in these birds. 
The pterylosis adheres throughout to one marked type, there being little variation except 
in the density of the plumage, which would seem to accord with temperature, the tropical 
forms being the more sparsely feathered. Excepting Phaethon, the gular sac is wholly or in 
part bare. The contour feathers appear to always lack aftershafts. The remiges are from 
26 to 40 in number, of which 10 are always long, strong, pointed primaries. There are 
usually 22-24 tail-feathers in the pelicans, but 12, 14 or 16 in the other genera. All have the 
oil-gland large, with a circlet of feathers and more than one orifice ; sometimes, as in the 
pelicans, it is protuberant, heart-shaped, as large as a pigeon egg, with two sets of six orifices ; 
in the gannets it is flat and disc-like. 
The palatal structure is extremely desmognathous ; there are no basipterygoids ; the 
maxiUo-palatines are large and spongy ; the mandibular angle is truncate ; other cranial 
characters appear under two aspects, one peculiar to the pelicans, the other common to the 
rest of the order. The sternum is short and broad, with transverse, entire or emarginate, 
posterior border ; the apex of the furculum commonly, if not always, anchyloses with the 
sternal keel. The upper arm bones are very long ; the tibia does not develop the very long 
cnemial apophysis or so called 'rotular process' seen in many Pygopodes. (See fig. 502.) 
The carotids are double ; tufted oil-gland, cceca and ambiens muscle are present. 
The species of this order are few — apparently not over fifty, of which the Cormorants 
represent half — very generally distributed over the world. 
