364 



SYSTEMATIC ZOOLOGY 



webbed, and there are numerous spines among the hairs ; in 

 one species these spines are over seven centimeters long. They 

 are not aquatic in habit, but resemble the duckbill in burrowing, 

 and have the toes provided with sharp claws. As their popular 

 name indicates, they feed largely on ants and other small insects, 





Fn;. 355. Echidna oculeata, the spiny ant-eater. (After Vogt and Sprecht, from Parker 



and Haswell's Manual.) 



and for this purpose have a long, slender, and protrusible tongue. 

 During the breeding season a temporary pouch is formed of the 

 skin on the ventral side of the body, in which the eggs are placed 

 when laid, and there the young remain for some time after hatch- 

 ing. After the breeding season the pouch disappears. In all 

 of the Monotremata nipples are absent, and the ducts from the 

 mammary glands open directly on the surface of the skin. 



SUBCLASS II. DIDELPHIA, OR MARSUPIALIA 



The Didelphia (Gr. &?, double, and SeX$iA\ womb), or Marsu- 

 pialia ( Lat. marsupium, pouch), sometimes called the Metatheria 

 (Gr. f^erd, between, and Bripiov, beast), are commonly distin- 

 guished by the marsupium. or pouch, which is attached to the 

 posterior part of the ventral abdominal wall ; but this pouch is 

 sometimes rudimentary and sometimes absent, and we have 

 already noted that a similar pouch occurs in some of the Mono- 

 tremata. This class is distinguished from the preceding by the 

 fact that there is no true cloaca, but distinct anal and urogenital 



