ii)4 



VEliTEBIiATE ANIMALS. 



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

 gravity of the hodj ; 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 toe.s in all 

 the Xntiitnrr.t arc 'inhhed to a greater or less extent, or, in other 

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

 or membrane between tin t les is stretched completely from toe to 

 toe, Imt in otliers the mcndu rni is divided between the toes, so that 

 t!ie feet arc only imjieitt th wtblel. As their aquatic mode of 



Fi'A- .iC!'. —Penguin {Ai't^uoiJiifes patii'jninra). 



life exposes them to great reductions of tenii)erature, the body in 

 the Natatorial Birds is closely co\'ered with feathers, with a thick 

 covering of do^vn next the skin. They are further protected against 

 Ijecoming wet whilst in the water liy the great development of the 

 ojl-gland at tlie tail, by means of which the dense ].)lumage is ke])t 

 con.stantly oiled. As a rule, tbe N^datoriiil Biivls are polygamous, 

 each male liaving sevo'al females ; and the young .-ire hatched in a 

 condition jiot re((niring assistance from tlieir ]iarents, being able to 

 swiiji abi>ut and ja'ocure food fur tliemselvcs .as .soon as they are 

 lilierat.'d finiii 1h,. ,M,-,r 



