OF VERTEBRATE ANIMALS 69 



both far and near. The ear a little more complete than in the 

 other ovipari, has no stones in the vestibule; the cochlea is 

 somewhat curved; there is a small bone, between the fenestra 

 ovalis and the tympanum, which is deprived of a conch, ex- 

 cept in the nocturnal genera. The organ of smell, concealed 

 in the base of the beak, has generally three cartilaginous tur- 

 binated bones and no sinus. The tongue is but slightly mus- 

 cular, and is supported by a bony projection of the hyoides. 

 The rings of the trachea are entire, at its bifurcation there is a 

 glottis or inferior larynx, where voice is produced; the supe- 

 rior larynx is very simple. The lungs, which have no lobes, 

 attached to the ribs, permit air to pass into several cavities of 

 the body, the breast, the axillae, and even of the bones; this 

 augments their specific lightness and multiplies respiration. 

 The upper maxilla is principally formed by the inter-maxillary 

 bones, and is prolonged backward into two arches, one inter- 

 nal made by the ossa palati, and the other external, by the 

 maxillar and jugal bones, both of which rest on the square or 

 tympanal bone, which is moveable; it is joined to the craniu 

 by elastic laminae. Both jaws are covered with horn, whic 

 supplies the want of teeth, and which sometimes has their form. 

 The stomach is composed of three parts more or less distinct: 

 the crop, which is sometimes wanting, the membranous stomach 

 furnished with numerous secretory follicles, and the gizzard, 

 which has two strong muscles, and is lined by a coriacious 

 membrane. In birds of prey, however, the gizzard is very 

 thin, and not very distinct from the other stomach. The spleen 

 small, the liver has two ducts, and the pancreas is considera- 

 te; there are two appendages to the rectum, sometimes one, 

 md in some genera none, which appear to be the remains of 



allantoid. 



The rectum, the ureters, and the spermatic vessels or the ovi- 

 luct, communicate with a cavity called the cloaca, which opens 

 it the anus. The testicles are internal and under the loins ; there 

 is but one ovary and one oviduct. Most birds copulate by the 

 simple approximation of the anus; some genera, however, have 

 a small canulated penis. The egg, detached from the ovary, 

 is composed of the germ and yolk only; it becomes enveloped 



