610 CLASS XVII. 



Section I. Dermatopoda. Feet palmate. 



Ornitliorhynchus Blumenb., Platypus Shaw, Dermipus WiE- 



/2 — 2\ 

 DEM. Eight horny teeth ( x — ^ j flat, destitute of fangs, composed of 



perpendicular horny tubules, the anterior narrow, long, the posterior 

 oval. Snout depressed, flat, broad; lower jaw narrower, shorter, 

 marked at the margin posteriorly by several transverse stria3. Body 

 hairy. Tail broad, depressed, beset with rigid hairs. 



The duck-billed animal, the water-mole of the English colonists. On the 

 structure of the organs of propagation we have already spoken. The ster- 

 num consists of four flat bony pieces placed one behind another, to which 

 the ribs are attached, and of a larger piece lying in front of these, which 

 has in some degree the form of an hour-glass, but in front terminates in 

 two transverse branches, on the anterior margin of which the furcular 

 clavicles are situated, and soon coalesce with them. The scapula forms, 

 with the other clavicle, the coracoid clavicle, the articular cavity for the 

 humerus. The coracoid clavicle descends obliquely from the articular 

 cavity to the lowest part of the lateral margin of the first and the anterior 

 part of the second sternal piece ; in front of it, and along the sides of the 

 first sternal piece is another bony plate, to which Meckel gave the name 

 of Clavicula coracoidea anterior, the os epicoracoideum. These two anterior 

 bony plates meet in the mid-plane and are covered below by the sternum. 

 Such also is the structure in the following genus Tachyglossus. The pelvis 

 is formed after the mammalian type. 

 I The spur of the male consists of a conical and perforate bony piece, 



covered by a horny investment, through which runs the excretory duct of 

 a gland situated on the thigh ; some observations, from which it had been 

 concluded, that the fluid secreted by this gland was possessed of venomous 

 properties, and that the spur was used by the animal as an oflfensive weapon, 

 have not been subsequently confiinned ; perhaps it has relation to copula- 

 tion. Meckel found in the female water-mole a small cavity in the same 

 situation which appeared to be adapted for the reception of the spur. 



The water-moles live in the rivers and lakes of New Holland and of 

 Van Diemen's Land. They dive and swim like water-birds and secure 

 their prey, whilst swimming, with their bill, as ducks do. They feed on 

 worms and insects; fragments of shell and parts of water-insects have been 

 found in their cheek-pouches and in their stomach. They dig holes of 

 twenty or more feet long, which have a double entrance, one close above 

 the water and another below the water, and ending in a larger space 

 covered with rushes and other dry plants. The young animal is naked, 

 and has a short beak with flexible jaws. The adults attain a length of 

 from seventeen to twenty two inches, from the anterior margin of the 

 upper jaw to the point of the tail, which is about five inches long. 



Sp. Oi'nitJiorki/nchus paradoxus 'Blvuienb., Abb.naturh. Gegenst. 41, Scheeb. 

 Tab. 63 B, GuER. Iconogr., Mammif. PL 36, fig. 2, Gov. R. Ayii., ed. ill., 



