448 ANIMAL LIFE-HISTORIES 



The somewhat similar habits of the American Alligator 

 {^Alligator Mississippiensis) are thus described by S. F. Clarke 

 (in The Journal of Morphology, 1891): — "The nest of the alligator 

 is very large, and is built by the female. A great quantity of 

 dead leaves and twigs, together with much of the finely-divided 

 humus underlying them, is scraped together into a low mound 

 about 3 feet high ; this varies considerably in its other dimensions, 

 being in some instances 8 feet in diameter at the base. The nests 

 are built on the bank of a stream or pool, and the female digs a 

 cave under water in the bank close to the nest. Careful examina- 

 tion of the largest nest found showed a root of a neighbouring 

 palmetto-tree, nearly an inch in diameter, running through it at 

 about a foot above the ground; there were also roots of a grape 

 vine growing near, which extended nearly through the nest. This 

 furnishes strong support to the statement of many of the hunters, 

 that the nests are used for more than one season. I could get 

 no evidence whatever that the nests are used more than once a 

 year. The eggs are laid near the top of the nest, within 8 inches 

 of the surface, are four or five layers deep, and have no regular 

 arrangement or uniform position of rheir axes in relation to the 

 nest. The number of eggs to a nest varies from twenty to thirty, 

 and averages twenty-eight; the maximum found was forty-seven." 



LIFE-HISTORIES, &c., OF BIRDS (AVES) 



All Birds, without exception, lay hard-shelled eggs, and at 

 tne time of hatching the young are either helpless (nidicolse), as in 

 the House-Sparrow, or else, as in Fowls, able almost at once 

 to run about and feed themselves (nidifugse). The eggs vary 

 greatly in number, size, and appearance, and are commonly, 

 though by no means always, laid in specially constructed nests, 

 the nature of which is even more diverse than their contents. 

 One parent, or each in turn, usually broods over the eggs, thus 

 supplying the heat which is necessary for development. The 

 skin on the under side of an incubating bird is plentifully supplied 

 with blood and sometimes is more or less bare; increased warmth 

 is the result. Sometimes, however, there is no such incubation, 

 and the requisite warmth is otherwise supplied. Parental affection 

 is commonly very strong, especially in those cases where there are 

 helpless nestlings, which would speedily die if not carefully tended. 



