320 NATATOUES. 



turn, where it terminates in the jejunum : the pancreatic duct enters 

 close by the ductus hepaticus. 



This was a female. The oviducts, &c. were like those in 

 other fowls. The male is . larger than the female, and the tes- 

 ticles, at the time it was shot, in January, were of this size : — 

 The males differ much in size, some being much larger than 

 others. Their breast-bone is different from the female's ; the cavity in 

 the bone in which the trachea takes the turn being only such as admits 

 of the turn, while that in the female is considerably larger. 



The Difference between the Wild and Tame Swan. 



The head of the wild swan is more like the head of the goose ; it 

 comes more to a point at the top, or rises higher; this is probably due 

 to the feathers. The neck is commonly much more straight ; and has 

 not that curve we often find in the tame swan. It never throws the 

 head backwards on the back between the wings. They never raise [the 

 wings] so as to make them hollow underneath, as the tame swan does. 

 They stand more straight on their legs : I believe their legs are rather 

 longer, and they walk better. 



A wild swan, that was shot in the year 1783-84, and had his 

 flight feathers cut short, and was kept through the summer, did not cast 

 those feathers ; nor did it in the winter 1784-85 ; but, about the month 

 of August 1785, it cast them. It threw off a great many feathers in 

 the summer of 1784, but whether he may be said to have moulted I do 

 not know. 

 Extract of a Letter from Mr. Davy to Mr. BanTcs, with the breast-bones 



of two Swans 1 , to shoiv the specific difference between those that breed 



in England, and those that only visit us in severe weather. 



" That with the trachea joined to it is the breast of a wild swan shot 

 in this parish last February. As almost all defenceless birds have a 

 sentinel upon the watch to give warning of danger to the flock, he con- 

 ceives the use of the hollow box in the septum of the breast-bone may 

 be to add loudness to the voice, which on being alarmed, somewhat 

 resembles the snorting of a horse in high mettle ; and that as this bird 

 soars veiy high where the cold of the air is piercingly severe, the length 

 of the trachea, by its curvature, enables it likewise to take in a larger 

 portion of air, and to give it a degree of warmth in this cavity of the 

 breast-bone before it suffers it to pass into the lungs. If he is not 

 mistaken, there is a peculiarity in the form of the lower end of the 



1 [viz. the Hooper [Cygnits fer-us, Yarrell], which lias the entosternal tracheal fold 

 vertical and confined to the keel, and the Bewick's Swan \Cygnu& Bewickii, Yarrell], 

 which has the tracheal fold horizontal. See Linn. Trans, vol. xvi. p. 449.] 



