ORNITHORHYNCHID& 123 



and the Ornithorhynchus teeth is of the most general character, 

 and that the two are certainly widely separated generically, even if 

 we do admit that they appear to possess a relationship nearer to 

 each other than to any other known groups of mammals." 



Eeverting to the description of the Duck-bill, we find that in 

 the cheeks are tolerably capacious pouches, which appear to be used 

 as receptacles for food. The limbs are strong and very short, each 

 with five well-developed toes provided with strong claws. In the 

 fore feet the web not only fills the interspaces between the toes, but 

 extends considerably beyond the ends of the long/'broad, and some- 

 what flattened nails, giving great expanse to the foot when used for 

 swimming, though capable of being folded back on the palm when 

 the animal is burrowing or walking on the land. On the hind foot 

 the nails are long, curved, and pointed, and the web extends only 

 to their base. On the heel of the male is a strong, curved, sharply 

 pointed, movable horny spur, directed upwards and backwards, 

 attached by its expanded base to the accessory bone of the tarsus. 

 This spur, which attains the length of nearly an inch, is traversed 

 by a minute canal, terminating in a fine longitudinal slit near 

 the point, and connected at its base with the duct of a large gland 

 situated at the back part of the thigh. The whole apparatus is so 

 exactly similar in structure to the poison-gland and tooth of a 

 venomous snake as to suggest a similar function, but evidence that 

 the Platypus ever employs its spur as an offensive weapon has, at 

 all events until lately, been wanting. A case is, however, related 

 by Mr. Spicer in the Proceedings of the Royal Society of Tasmania 

 for 1876 (p. 1 62), of a captured Platypus inflicting a severe wound by 

 a powerful lateral and inward movement of the hind legs, which wound 

 was followed by symptoms of active local poisoning. It is not improb- 

 able that both the inclination to use the weapon and the activity of the 

 secretion of the gland may be limited to the breeding season, and 

 that their purpose may be, like that of the antlers of deer and 

 many similar organs, for combat among the males. In the young 

 female the spur is present in a rudimentary condition, but it dis- 

 appears in the adult of that sex. 



The Platypus is aquatic in its habits, passing most of its time in 

 the water or close to the margin of lakes and streams, swimming 

 and diving with the greatest ease, and forming for the purpose of 

 sleeping and breeding deep burrows in the banks, which generally 

 have two orifices one just above the water level, concealed among 

 long grasses and leaves, and the other below the surface. The 

 passage at first runs obliquely upwards in the bank, sometimes to 

 a distance of as much as fifty feet, and expands at its termination 

 into a cavity, the floor of which is lined with dried grass and 

 leaves, and in which the eggs are laid and the young brought up. 

 The food consists of aquatic insects, small crustaceans, and worms, 



