TEE RESPIRATOBY APPARATUS IN BIRDS. 565 



the parietes of the abdomen, and those of the pelvis. Inwardly, they are in 

 contact with the intestinal mass and the testicles or ovaries. Below and in front, 

 they rest on a fibrous septum, which in all birds divides the abdominal cavity 

 into two smaller cavities : one anterior, which represents the abdomen and 

 lodges the liver, the other posterior, which represents the pelvis and contains 

 the stomach and intestines. This fibrous septum is extremely remarkable in 

 large birds, particularly the Ostrich, in which it has been described by Perrault 

 as a transverse diaphragm ; it is inserted into the entire circumference of the 

 pelvic bones, and sustains the stomach as well as the intestinal tube. Below and 

 behind, the abdominal reservoirs lie on the intestines. Above, these sacs cover 

 the inferior face of the kidneys, and there furnish three prolongations : 1. A 

 supra-renal prolongation. 2. Two femoral prolongations. 



" The supra-renal prolongation leaves the principal reservoir at the postero- 

 external part of the kidneys ; from thence it passes obliquely upwards and 

 forwards, to spread over the superior surface of the kidney, which it depresses 

 when the abdominal sac is inflated. Arrived at the internal border of the 

 kidneys, these prolongations are introduced between the transverse processes of 

 the sacral vertebrae, and ascend from behind forwards to the height of the two 

 first dorsal vertebra, forming two triangular canals situated above the sacrum, 

 in the sacral channels, and separated from one another by a series of correspond- 

 ing spinous processes. The supra-renal prolongations are not present in all 

 birds ; they are particularly observed in the Gallinacas and diurnal rapacious 

 birds. In some Palmipeds— the Swan, for example — they are equally developed ; 

 in the Ostrich, they are replaced by the supra-spinal canals. 



" The femoral prolongations' are two in number — an anterior small and a 

 posterior large ; they arise from the abdominal reservoir at the cotyloid cavities, 

 and leave the pelvis in traversing the bony opening through which the crural 

 vessels pass ; after clearing the limits of these cavities, they spread around the 

 coxo-femoral articulation, and terminate in a caecum in the majority of birds. 

 In diurnal birds of prey, they communicate with the femoral canal by an orifice 

 situated at the anterior part of the great trochanter.- These prolongations, very 

 developed in the Ostrich, also open in it into the femoral cavity ; it is not 

 without surprise that we see this arrangement, which is peculiar to birds remark- 

 able for their rapidity and power of flight, also present in those to which asrial 

 locomotion has been entirely denied. The abdominal reservoirs communicate 

 with the lung by an orifice situated beneath the fibrous arch of the diaphragm, 

 and disposed like the rose of a watering-can." 



Communication of the Reservoirs with the Bones. — " The communi- 

 cations of the respiratory apparatus with the skeleton in birds are extremely 

 numerous. We will successively examine those belonging to each reservoir. 



" The bones which receive air from the thoracic reservoir are : 1. The 

 anterior clavicle, which is perforated at its two extremities. 2. The posterior 

 clavicles, which are also perforated a little below their scapular extremity. 3. 

 The sternum which presents two series of openings — the middle ones that con- 

 duct the air into the sternal ridge, and the lateral ones, very small, six to eight 

 in number, corresponding to the intercostal spaces. 4. The scapulEe, which offer 

 one or more apertures at their anterior extremity, and receive the air for the 

 subscapular prolongation. 5. The humerus, which obtains the air for the 

 humeral prolongation by a fossa situated at the inferior and internal part of its 

 articular head. 6. The sternal ribs, which allow the atmosphere to penetrate 



