952 SYSTEMATIC SYNOPSIS. — STEGANOPODES. 



deposited in a rude nest on the ground, on rocky ledges, or on low trees and bushes in the 

 vicinity of water. Tlie dietetic regimen is exclusively carnivorous, the food being chiefly 

 iish, sometimes i)ursued under water, sometimes plunged after, sometimes scooped up. In 

 accordance with this, we find the alimentary canal to consist of a capacious distensible oesoph- 

 agus not developing a special crop, a large proventriculus with numerous solvent glands, a 

 small and very moderately muscular gizzard, rather long and slender intestines, and an ample 

 globular cloaca. The cfeca are small, in some cases fuuctionless, or only one csecuin exists. 

 The tongue is extremely small, a mere kuob-like rudiment (as in piscivorous Kingfishers). 

 The characteristic gular pouch varies greatly in development, T)eing enormous in Pelicans, but 

 inconspicuous in Tropic-birds. The condition of the external nostrils is a curious feature ; 

 they are generally obliterated in the adult state, but in some species, like the Tropic-hird, 

 they remain open. Intrinsic syringeal muscles may be present or absent in birds of this 

 order. But the most notabh; fact in connection with the respiratory system is the extraordi- 

 nary pneumaticity of the body in some of the families, this reaching its height in Pelicans and 

 Gannets. The interior air receptacles are of an ordinary chai'acter, but the anterior of these 

 cells are more subdivided than usual ; from them, air gets under the skin through the axillary 

 cavities, and difi'uses over tlie 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 shalhtw, 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 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, tliere being little variation except 

 in density of plumage, which would seem to accord with temperature, tro])ical forms being tlie 

 more sparsely feathered; however, it is peculiar to some extent in Anhingidce. Excepting 

 Phaethon, the gular sac is wholly or in part bare; aftershafts wanting or minute {Fregata). 

 The remiges are from '^(J to 4(1 in number, of which 10 are always long, strong, pointed prima- 

 ries. There are usually 22-24 tail-feathers in Pelicans, but 12, 14, or 10 in other sfeTiera. 

 All have the oil-gland large, with circlet of feathers and more than one orifice; sometimes, as 

 in Pelicans, it is protuberant, heart-shaped, as large as a Pigeon's egg, with 2 sets of 6 ori- 

 fices; in Gannets it is flat and disc-like. The carotids are double as a rule, but single in 

 Darters, some Pelicans, and a Gannet ; the great pectoral muscle is likewise double, witii a 

 different mode of insertion of its two divisions into the humerus. The ambiens is normally 

 present; other muscles of the thigh vary to a degree. 



The palatal structure is extremely desmognathous ; no basipterygoids ; maxillo-palatines 

 large and spongy ; mandibular angle is truncate ; other cranial characters appear under two 

 aspects, one peculiar to Pelicans, the other common to the rest of the order. Tiie cervical 

 and cervicodorsal vertebrae are from 15 in Phnethontidce and Fregatidee to 17-20 in the other 

 four ftimilies ; and the 8th or 9th one has a peculiarity of its articulation which causes the 

 kink or bend of the neck at that place so characteristic of these birds, but best marked in 

 Cormorants and Darters. The sternum is short and broad, with transverse, entire or emar- 

 giuate, posterior border. The upper arm bones are very long; tlie tibia does not develop 

 the very long cnemial apophysis or so-called " rotular process" seen in many Pygoiiodes. 

 (See fig. 675.) 



The species of this order are few — apparently not over 70, of which Cormorants repre- 

 sent one half — very generally distributed over the world. Of the 6 families, I'haethontidce 

 and FregatidfB differ as much from each other as both do from the other 4 — Phalacrocoracidce, 



