144 AMERICAN SWAN. 



its average diameter 7 twelfths. The rectum is 7 inches in length, 8 

 twelfths in diameter. The coeca 11 inches long, their diameter for 3 

 inches only 2 twelfths, in the rest of their extent from 3 to 4^ twelfths, 

 the extremity obtuse. The cloaca is of moderate size and of a globu- 

 lar form, with longitudinal rugae on its inner surface ; that of the rec- 

 tum is also longitudinally rugous, and covered with flattened papillae. 

 The transverse muscular fibres of the intestine are all very well marked 

 in its whole extent ; the inner surface is covered with minute promi- 

 nences, arranged in regular series ; the anterior portion beautifully 

 villous. 



This species has 11 ribs, the anterior rib not joining the sternum. 

 The lungs are of large size, extending from the second to the ninth 

 rib, and having, therefore, 7 deep grooves on their upper and inner 

 surface. The trachea is 20 inches long ; its breadth at the anterior 

 part 9 twelfths. It gradually diminishes to 7 twelfths, and is much 

 flattened until about 6 inches from the furcula, when it becomes gra- 

 dually cylindrical, reaches the curve of the furcula, bends a little up- 

 wards, and enters a cavity formed in the sternum, along which it 

 passes to the length of 6 inches, bends upon itself horizontally, returns, 

 passes up between the crura of the furcula, bends backwards, and en- 

 ters the thorax, its diameter in this part of its course being 7 twelfths. 

 The inferior larynx is laterally compressed, its last rings united. Ap- 

 pended to the last or semilunar ring on each side is a narrow membrane, 

 terminated by a very slender half ring ; the membrane intervening be- 

 tween it and the first bronchial ring is large. The bronchi themselves 

 are very short, compressed at the commencement, enlarged at the middle 

 into a roundish cavity 7^ twelfths in diameter, afterwards cylindrical ; 

 their entire length If inch. The lateral or contractor muscles of the 

 trachea are large, and come ofi" at the curve of the furcula, not following 

 the course of the trachea within the sternum, but passing directly across 

 to near the inferior larynx, where they terminate at the distance of 1^ 

 inch. The rings of the trachea are broad and well ossified ; there are 

 148 to the curve, 40 between the lower larynx and its exit from the 

 sternum. The right bronchus has 23, the left 21 rings. 



In the external or subcutaneous cellular tissue of this bird, on the 

 right side, over the thorax, was found a cartilaginous tumour of a 

 roundish form, of which the greatest diameter was 1^ inch. 



Dr Shakpless, in a paper published in the American Journal of 



