294 



YERTEBliATE ANIMALS. 



long neck. The legs are short, and are placed behind the centre of 

 gravity of the body ; this position enabling them to act admirably 

 as swimming paddles, at the same time that it renders the gait upon 

 dry land comparatively awkward and shuffling. The toes in all 

 the Katatores are vMed to a greater or less -extent, or, in other 

 words, are united by a membrane (fig. 208, B). In many the web 

 or membrane between the toes is stretched completely from toe to 

 toe, but in others the membrane is divided between the toes, so that 

 the feet are only imperfectly webbed. As their aquatic mode of 



reii.L^iiiii {Aj'teiwtbjles poli'ijnntcn). 



life exposes them to great reductions of temperature, the body in 

 the Natatorial Birds is closely covered with feathers, with a, thick 

 covering of down next the skin. They are further protected against 

 becoming wet whilst in the water by the great development of the 

 -oil-gland at the tail, by means of which the dense plumage is kept 

 constantly oiled. As a rule, the Natatorial Birds are polygamous, 

 each male having several females ; and the young are hatched in a 

 co7idit)on not requiring assistance from their parents, being able to 

 swim about and prtjcure food for themselves as soon as they are 

 liberated from the egg. 



