PENGUIN 



Figure 2-10. 



APTERYX 



Some extremes of the birds. 



like feathers are observed. The feathers of the region in front 

 of the eye tend to be hair-Hke. 



The scalation of the leg in the pigeon is modified; scutes 

 are formed by the fusion of several scales. Small feathers 

 may come out of the middle of some of the scutes. In some 

 birds, such as the Barn Owl or the pelican, the leg is covered 

 by small polygonal scales, and, in the case of Barn Owl, 

 small feathers are observed growing out from between the 

 scales or from the posterior margin of the scales. 



Mammals 



Mammals are defined as having hair and mammary (or 

 milk) glands, which give the group its name. 



Monotremes The Spiny Anteater (or Echidna) and the 



Platypus are unique kinds of mammals (Figure 2-11) which 

 lay eggs much like those of a reptile. The first has the snout 

 elongated and tapered; the second has a duck-like bill 

 covered by hairless, leathery skin. E.xternal ears or auricles 

 are lacking. The hair has been modified into spines in the 

 case of the Echidna. The tail is short and covered with 

 spines. The limbs are stout with heavy claws for digging. In 

 the case of the Platypus the body is covered with soft hair, 

 the short legs have long, webbed digits, and the tail is 

 flattened for swimming. The female Echidna has a crescentic 

 marsupial fold on the belly; nipples are lacking in both 

 genera. Males of these animals have a poisonous spur on 

 the hitid legs. 



Marsupials The female opossum has a pouch or mar- 

 supium in the inguinal region, in which the young undergo 



nostril, 



TACHYGLOSSUS 



ORNITHORHYNCHUS 



Figure 2-1 1. Two of the living monotremes. 



LIVING REPRESENTATIVE VERTEBRATES • 29 



