THE DUCK-BILLS. 231 
naked and devoid of pads. Three pairs of many-cusped molar- 
teeth in each jaw, of which the foremost is the smallest in the 
upper, and the hindmost in the lower jaw; these teeth disap- 
pearing in the adolescent animal, and their place taken in the 
adult by hard horny plates. Horny spur on hind foot of male 
very large. Hemispheres of the brain smooth. 
The single genus and species by which the family is now 
represented is confined to Australia and Tasmania. 
THE DUCK-BILLS. GENUS ORNITHORHYNCHUS. 
Ornithorhynchus, Blumenbach, Voigt’s Mag. Naturkunde, 
vol. il., p. 205 (1800). 
Form elongate and depressed; each foot with five toes, 
severally furnished with long claws, those on the fore feet 
being broad and blunt, while those of the hinder pair are 
compressed and pointed. Beak smooth, short, and evenly 
rounded, its junction with the head, both above and below, 
defined by a flap of skin; cheeks furnished with pouches, 
THE DUCK-BILL. ORNITHORHYNCHUS ANATINUS. 
Platypus anatinus, Shaw, Natur. Miscell., vol. x., pl. 385 (1799). 
Ornithorhynchus paradoxus, Blumenbach, Voigt’s Mag. Natur- 
kunde, vol. ii., p. 205 (1800). 
Ornithorhynchus rufus, et O. fuscus, Péronand Lesueur, Voyage 
Terres, Austral., atlas, pl. xxxiv. (1807). 
Ornithorhynchus brevirostris, Ogilby, Proc. Zool. Soc., 1831, 
W550. 
Ornithorhynchus crispus, et O. levis, Macgillivray, Mem. Wern. 
Soc., vol. vi., pp. 128, 132 (1832). 
Ornithorhynchus anatinus, Gray, List Mamm. Brit. Mus., 
p. 191 (1843); Thomas, Cat. Marsup. and Monotr. Brit, 
Mus., p. 388 (1888). 
(Plate XXX VII.) 
