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MAMMALIA ORDER XII. MONO TRE MA TA. 



Fig. 116 -DUCK-BILI. 

 ( Orn ithorhynchus a natinus). 



pointed. The beak is smooth, short, and evenly-rounded in front, with a 

 flap of skin marking its junction with the head ; and the cheeks have 

 pouches for the storage of food. In length the adult male measures about 



18 in. to the root of the tail, which is one- 

 third the length of the head and body ; but the 

 female is considerably smaller. The duck-bill 

 is confined to the fresh- waters of Tasmania 

 and Australia, where it especially frequents 

 still and deep pools in rivers with banks 

 suitable for the construction of its long and 

 tortuous burrows ; these burrows generally 

 having two entrances, the one situated above, 

 and the other below the level of the surface of 

 the water. In length a burrow may be as 

 much as 20 ft., and at its extremity it expands 

 into a capacious chamber, which is lined at the 

 breeding season for the reception of the white 

 eggs usually two in number. Here in due 

 course they are hatched, the female sitting 

 upon them in the same manner as a bird, since 

 the pouch is not sufficiently large for their 

 reception. When first hatched, the young 

 are completely naked and helpless, and are fed 

 with milk in the manner indicated above. As soon as they are able to feed, 

 they are supplied with fresh-water snails and insects such as form the chief 

 nutriment of their parents. Duck-bills are mainly nocturnal animals, 

 passing the day rolled up asleep in their burrows. 



Very different, both in appearance and their mode of life, to duck-bills are 

 the echidnas, or spiny ant-eaters, constituting the family Echidnidce. In 

 place of being aquatic, these Monotremes are terrestrial and 

 Echidnas. nocturnal in their habits, while the sexes lack that discrep- 

 ancy in size which forms such a marked feature in the 

 preceding group. In place of the duck-like beak of the Ornithorhyiichus, 

 the muzzle of the echidnas forms a long, slender beak, which is completely 

 devoid of teeth at all ages, and is suited to the long, extensile, worm-like 

 tongue characteristic of all ant-eating mammals. The fur is so thickly inter- 

 mingled with short and stout spines, not unlike those of the hedgehogs, that 

 sometimes little more than the latter are visible. The tail is quite rudi- 

 mental ; the short, sub-equal limbs have unwebbed toes, furnished with 

 broad, powerful, nail-like claws, and, although the soles of the feet are 

 provided with soft, fleshy cushions, there are no pads. A peculiar feature 

 connected with the mouth is the presence of spines on both the palate and the 

 tongue. During the breeding season the pouch of the female is much more de- 

 veloped than in the duck-bill ; and the hemispheres of the brain differ from 

 those of the latter in being well convoluted. The smooth surface and bird-like 

 form of the skull is very characteristic of the family, and the lower jaw is 

 remarkable for its extreme slenderness. These animals subsist exclusively 

 on ants, which are dug out by the powerful claws and licked up by the 

 extensile tongue. The large size of the pouch enables the female to carry 

 about with her the two eggs, which in due course are hatched by the heat of 

 her body. The echidnas have a wider geographical distribution than the 

 duck-bill, and are represented by two genera, one of which ranges from 



