CYGNUS. SWAN. 651 



elevated, compressed beneath ; anterior toes longer than the 

 tarsus, the outer a little shorter than the third, all reticulate 

 as far as the second joint, then scutellate ; the inner with a 

 broad, somewhat two-lobed margin, that of the outer thick 

 and narrow; the interdigital membranes reticulate, full. 

 Claws strong, arched, compressed, convex above, rather ob- 

 tuse, that of the third toe with the inner side expanded and 

 the tip rounded. 



Plumage moderately full, close, firm, unless on the head 

 and neck. Feathers of the head very small and oblong, of 

 the neck narrow and soft, of the other parts ovate and 

 rounded. The scapulars large ; the numerals eight or ten. 

 The wings very long, rather broad, convex, with about 

 thirty-two quills ; the outer four or five quills more or less 

 cut out toward the end, the second and third longest, the 

 first little shorter ; the secondaries broad and rounded. The 

 tail is short, rounded, of from eighteen to twenty-four rather 

 broad, rounded feathers. In each species the number is not 

 very definite. Thus, in Cygnus Bewickii, it is generally 

 eighteen, but sometimes twenty. 



The Swans inhabit chiefly the temperate and cold regions 

 of the globe. Eight species are known, of which some have 

 a bare fleshy knob at the base of the upper mandible above, 

 while in others that part is flat or concave. Another remark- 

 able difference occurs with respect to the trachea, which in 

 some follows the usual course, while in others it first enters 

 the sternum, forming a loop, in the same manner as in the 

 Cranes. Notwithstanding these differences, it seems inju- 

 dicious to separate the group into distinct genera, as the 

 species otherwise agree in all essential respects. Nor do 

 their habits appear to be affected by these modifications of 

 structure. Hence we may infer that in other cases, when 

 two birds resemble each other in form, the presence of a 

 frontal knob in one is not sufficient to induce its generic 

 separation. Similar differences in the windpipe occur in the 

 genus Platalea. 



The Swans reside in marshes, on lakes, pools, and rivers. 

 They frequently search for food in the pastures close to the 

 Avater, walking slowly and heavily ; but in general they 



