436 



ZOOLOGY 



SECT. 



sea-shore, as in Penguins and Auks, or on the ledges on inaccessible 

 cliffs, as in the Sooty Albatross {Dimnedea fuliginosa) ; but as a rule 

 a nest is constructed for their reception by the parent Birds. This 

 may be simply a hole in the sand, as in the Ostrich ; a mere 

 clearing on the hill-side surrounded by a low wall of earth, as in 

 the Wandering Albatross {Diomedea exulans) ; or a cylinder with 

 excavated top, built of grass, earth, and manure, as in the Molly- 

 mawks (Diomedea melanoplirys, etc.). It may take the form of a 

 burrow, as in many Petrels, Kingfishers, and Sand-martins, or it 

 may be more or less elaborately built or woven of sticks, moss, 

 leaves, hair, or feathers, showing every stage of constructive skill, 



Fig. 1074.— GallUB bankiva (domestic Fowl). Semi-diagrammatic view of the egg at the time 

 of laying, a, air-space ; alb. dense layer of albumen ; alb', more fluid albumen ; bl. blasto- 

 derm ; ch, chalaza ; .t/i. shell ; nk. m. shell-membrane ; sh. m. 1, sh. m. 2, its two layers separated 

 to enclose air-cavity. (From Marshall's Embryology, slightly altered.) 



from the rude contrivance of sticks of the Pigeon and Eagle, to the 

 accurately constructed cup- or dome- shaped nests of many familiar 

 Passeres. In the Tailor-Bird {Orthotomus) it is formed of leaves 

 sewn together, the beak acting as needle : in a Malayan Swift 

 {Gollocalia) it is largely built of the secretion of the Bird's buccal 



glands. 



The number of eggs laid varies from 15 — 18 in the Partridge, to 

 a single one in many Sea-birds and in the Kiwi. As a rule the size 

 of the eggs bears some proportion to that of the Bird, the smallest 

 being those of Humming-birds, the largest those of the Moas and 

 of .iEpyornis : but in Apteryx the egg is of disproportionate size — 

 as large as a Swan's or an Albatross's, the Kiwi itself being no 

 larger than a Barn-door Fowl. 



