PALMIPEDES. 261 



Tropic-birds]. Ou land, where they seldom resort except to breed, they perch upon trees. [They are 

 closely related by affinity to the Gannets.] 



Several species are known, with white plumage, more or less varied with black, [and tinged in some with roseate,] 

 which do not exceed the size of a Pigeon. 



The family of 



Lamellirostres 



Is distinguished by a thick bill, invested with a soft skin rather than with true horn, [the 

 fact being, that the corneous portion is restricted to the nail-like extremity, the rest corre- 

 sponding to what is known as the cere] : its edges supplied either with laminae, or small 

 teeth, [which are modifications of each other] : the tongue large and fleshy, with a dentelated 

 border. Their wings are of moderate length. They live more in fresh waters than in the 

 sea : and, in the greater number, the trachea of the male is dilated near its bifurcation into 

 capsules of various form. Their gizzard is large, very muscular, and the coeca [generally] 

 long. [These birds lay numerous spotless eggs, and the young follow their parent as soon 

 as hatched.] 



The great genus of 



The Ducks {Anas, Lin.) — 

 Comprehends those Palmipedes which have a large and broad bill, the edges of which are beset with 

 salient laminae placed transversely, and the purport of which appears to be for straining off the water 

 when the bird has seized its prey. They divide into three subgenera, the limits of which, however, 

 are not very precise. 



The Swans {Cyynus, Meyer) — 

 Have the bill of equal breadth throughout, and higher than wide at the base ; the nostrils placed about 

 midway: and the neck exceedingly elongated, [possessing twenty-three vertebrae*]. They are the 

 largest birds of this genus, and feed chiefly on the seeds and roots of aquatic plants, [togetlier with the 

 grass which grows near the brink of water]. Their intestines, and cceca more especially, are accord- 

 ingly very long. Their trachea has no inflation or labyrinth. 



[Swans are essentially modified Geese, and like the latter are exclusively vegetable feeders, with 

 similar plumage in both sexes, which is moulted once only in the year, and undergoes no seasonal va- 

 riation of colour. They attack with the same hissing note, strike similarly with their wings, and the 

 male guards the female during incubation, and accompanies her while followed by her brood. They 

 fall into two subdivisions. 



In the first, the trachea, after descriliing a slight curve towards the sternal ridge, proceeds to the 

 lungs without entering any cavity in the bone. When swimming, they often erect the tertial plumes 

 of the wing, in an elegant manner. Three of the four species have a fleshy caruncle over the base of 

 the upper mandible, beneath which the bone is protuberant. 



The Mute Swan (Anas olor, Gmelin), or common domesticated species, the adults of which are wholly pure 

 white, with a reddish bill, surmounted by a black protuberance, and leaden-black feet ; young, grey, with the bill 

 lead-coloured. The wild breed (C. immutabilis, Yarrell) is rather smaller, with the rostral protuberance less 

 developed in the few specimens examined : there is also a semi-albino domestic race, with feet whitish, or par- 

 tially so, and reported to have white cygnets, which is termed the Polish b'ltan by the dealers ; it varies in size, 

 some attaining the largest dimensions of the ordinary tame breed. We are satisfied, from anatomical examina- 

 tion, that these are all specifically the same. The wild race is rarely met with in Britain. These birds do not 

 appear to breed before the third year. 



The Black Swan {A. atrala, Latham; A. plutonia, Shaw).— Less than the preceding, and not so elegant in its 

 conformation, with its tertials curled upwards: colour black, with the exception of its white primaries, and the 

 bdl and naked skin at its base, which are red. It is common in New Holland, and propagates readily twice a 

 year, or oftener, when brought to Europe. 



The Black-necked Swan (C. nigricQll\s).—\i\i.\ie:, witli black neck and tips of the primaries ; the sides of the 

 head white, and bill and feet orange, the former having a black protuberance. Common in South America. 



The smallest of all, or Duck-billed Swan (C. anatoides. King.), is also from South America, inhabiting towards the 

 Straits of Magellan. Colour pure white, with black tips to the primaries, and bill and feet orange : the former 

 having no basal protuberance. With the exception, therefore, of the common mute species, this division pertains 

 to the southern hemisphere. 



The rest have the trachea elongated as in the Cranes, and similarly entering a cavity in the sternal 



* We have found this number in four species, viz., C. olor, alruCui, muiicus, and Bcaickii,—Eo. 



