MANUAL OF ZOOLOGY. 



Prey, Parrots, Cuckoos, Kingfishers, Trogons, Anserine birds, Storks, 

 Cormorants. 



2. Schizognathcc. Maxillo-palatine processes of the maxillae separated 

 by a wider or narrower cleft. Vomer long and pointed in front, narrow 

 behind. Ex. Plovers, Gulls, Penguins, Cranes, Fowls, Sand - grouse, 

 Pigeons. 



3. sEgithognathce. Maxillo-palatine processes separated by a cleft. 

 Vomer truncated in front, narrow behind. Ex. Perching Birds, Swifts, 

 Woodpeckers. 



4. Dromceognathce. Vomer broad behind, interposing between the 

 pterygoids, the palatine bones, and the basi-sphenoid rostrum. This divi- 

 sion includes only the Tinamous ( Tinamomorphtz). 



The thoracic cavity is bounded behind by the dorsal verte- 

 brae, which are usually, as before said, anchylosed to one ano- 

 ther to a greater or less extent. Laterally, the thorax is bounded 

 by the ribs, which vary in number from six to ten pairs. In 

 most birds, each rib carries a peculiar process the " uncinate 

 process " which arises from its posterior margin, is directed 

 upwards and backwards, and passes over the rib next in succes- 

 sion behind, where it is bound down by ligament. The first 

 and last dorsal ribs carry no uncinate processes, and in some 

 cases the processes continue throughout life as separate pieces 

 (fig. 323, B). Anteriorly, the ribs articulate with a series of 

 straight bones, which are called the " sternal ribs," and which 

 in reality are to be looked upon as the ossified " costal carti- 

 lages." These sternal ribs (fig. 323, B) are in turn movably 

 articulated to the sternum in front, and " they are the centres 

 upon which the respiratory movements hinge" (Owen). In 

 front the thoracic cavity is completed by an enormously-ex- 

 panded sternum or breast-bone, which in some birds of great 

 powers of flight extends over the abdominal cavity as well, in 

 some cases even reaching the pelvis. The sternum of all 

 birds which fly, is characterised by the presence of a greatly- 

 developed median ridge or keel (fig. 323, A), to which are 

 attached the great pectoral muscles which move the wings. 

 As a general rule, the size of this sternal crest allows a very 

 tolerable estimate to be formed of the flying powers of the bird 

 to which it may have belonged ; and in the Ostriches and 

 other birds which do not fly, there is no sternal keel. At its 

 anterior angles the sternum exhibits two pits for the attach- 

 ment of the coracoid bones. 



The scapular or pectoral arch consists of the shoulder-blade 

 or scapula, the collar-bone or clavicle, and the coracoid bone, 

 on each side. The scapula, as a rule (fig. 323, A, s s\ is a 

 simple elongated bone, not flattened out into a broad plate, 

 and carrying no transverse ridge, or spinous process. Only a 



