STEGANOPODES: TOTIPALMATE BIRDS. 719 



observed among birds. It is represented by six genera, all North American, each the type 6f 

 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 witli 

 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 

 tlie 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 siaecies, like the tropic-bird, they remain so ; but they are generally 

 completely obliterated iu 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 tbe 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 diftuses 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 and the skin, this also containing air, admitted from the larger spaces by numerous 

 minute orifices close to the roots of the featbers. 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 i)terylosis adheres throughout to one marked type, there being little variation except 

 m 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 iu the 

 pelicans, it is protuberant, heart-shaped, as large as a pigeon egg, with two sets of six orifices ; 

 iu the gannets it is flat and disc-like. 



The palatal structure is extremely desmognathous ; there are no basipterygoids ; the 

 maxillo-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 lf)ng ; 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, coeca 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. 



