282 THE BIRDS 



and the scrub-covered plains of Patagonia Rheas are very incon- 

 spicuous, owing to the greyish-blue colouring of their plumage, 

 which causes them to merge into the distant haze, rendering them 

 almost invisible even at a short distance. 



All the remaining birds are included in the great division 

 Neorniltus carinatae, an enormous class of birds comprising a 

 vast number of orders, families and species, whose chief charac- 

 teristic lies in the fact that, with a few exceptions, they all have 

 a keel to the sternum. It is impossible here to do more than give 

 a brief description of some of the more interesting and important 

 groups of the Carinate birds, and we will first consider the aquatic 

 birds, for amongst these we find the oldest types, and a very large 

 proportion of all modern birds are aquatic or semi-aquatic 

 swimming or wading birds. 



The Penguins are an extremely archaic group of birds inhabiting 

 the Southern Ocean, for the most part passing their lives in the 

 icy waters of the Antarctic seas. Like the Ratitce, the Penguins have 

 lost the power of flight, but the wings are modified into swimming 

 organs, and the birds lead an aquatic existence, and are scarcely 

 seen on land except in the breeding season. They are curious- 

 looking creatures that appear to have no legs, as the limbs are 

 encased in the skin of the body, and the large, flat feet are set so far 

 back that the birds waddle along on land in an upright position in 

 a very ridiculous manner, carrying their long, narrow flippers held 

 out as if they were arms. When swimming, the Penguins use their 

 wings as paddles, while the feet are used for steering. The bones 

 of the wings are highly compressed and inflexible, so the wings 

 cannot be closed, but they work freely from the shoulder in a 

 rotatory manner, and the muscles that move them are remark- 

 ably strong. The name " Penguin " is said to have been derived 

 from " pin- wing/' i.e. pinioned wing. The family includes several 

 species, of which the most important are the King Penguin, the 

 Emperor Penguin, the Gentu Penguin, the Adelie-land Penguin, 

 the Rock-hopper, the Yellow-crested Penguin, the Blue Penguin, 

 the Black-footed Penguin, and the Jackass or Cape Penguin. 



In their habits Penguins are usually gregarious ; in the sea 

 they swim together in " schools," and on land assemble in great 

 numbers in their "rookeries." They are very methodical in their 

 ways, and on leaving the water the birds always follow well 



