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THE POPULAR SCIENCE MONTHLY 



forms a broad fold which falls over the brow, and furnishes an excel- 

 lent protection for the eyes when the animal is digging in the banks 

 of the streams. The nostrils are close to the end of the upper jaw. 

 In the lower jaw, or rather in the lower part of the mouth, are a num- 

 ber of elevations and depressions which run from the interior of the 

 mouth outward through the protecting skin, and serve, like similar 

 features in the duck, to let the water run out of the mouth when the 

 animal is eating in the thin mud. Within the mouth is a pouch in the 

 cheek, which is used as a place for preserving food. Four horny teeth 

 are set in each jaw, of which the front ones are long and narrow, the 

 others oval and hollow-crowned. The eyes are small and brown, set 

 close down by the bill, and look upward. The ear is entirely hidden 

 under the skin, yet the animal hears very well. The fore feet have five 

 long toes, much alike, with thick, rounded claws ; the toes are con- 

 nected by a skin which extends over the claws when the animal is swim- 

 ming, but is drawn back when it is digging. The skin of the hind foot 



reaches only to the base of the claws. 

 The males when grown have also a 

 movable, sharp spur on the hind foot. 

 The milk-glands are in the lower part 

 of the body, but are not marked by 

 any teats ; the glands swell out on 

 sucking, and the projection thus formed 

 is seized by the broad, soft mouth of 

 the young. It was formerly thought 

 that the ornithorhynchus laid eggs ; 

 but it is now known that it brings 

 its young alive into the world from a 

 double uterus through the so-called 

 urogenital canal. The animal chooses 

 its abode in quiet places on rivers 

 and ponds, wdiere the large-leaved wa- 

 ter-plants afford it sure concealment, 

 and the steep, muddy banks allow it 

 to dig deep holes, often fifty feet in 

 length. It is extremely shy, cautious, 

 and alert, and generally swims around 

 under the water, only raising its head 

 for breath, but seldom high enough to 

 be shot at. The young, born about 

 the beginning of December, are put 

 by the mother in a nest which she has prepared at the end of the' 

 burrow, and has lined with dry grass. They may be caught by 

 digging them out. They do very well in an aquarium, and make 

 comical, playful pets. The grown animals sleep through most of the 

 day rolled up into a ball, but are lively at night. When free, they 



Fig. 3. A, fore foot of the Ornithorhyn- 

 chus; B, hind foot ; a, spur. 



