THE ORNITHORHYNCHUS. 



there is no projecting ear, but merely an auditory aperture, 

 which the animal has the power of opening and closing at 

 pleasure, situated behind and external to the eye. The beak, 

 which strongly resembles that of the shoveller -duck, and is the 

 most characteristic part of this singular mammal, consists of 

 two flat projecting cartilaginous lips, or mandibles, slightly 

 serrated at the edges. This organ is of a dirty greyish black 

 colour, and covered with innumerable dots , and at the base 

 of each mandible is a loose and broad fold of skin, of the same 

 colour as the beak, and to this fold, or rather these two folds 

 of skin, different uses have been assigned. Sir E. Home con- 

 sidered them as intended to prevent the animal pushing its 

 beak too deep into the soft mud, while Mr. G. Bennett, who 

 studied this animal in its native haunts and also in captivity, 

 is of opinion that they protect the eyes when the animal 

 is burrowing for food in the mud. The nostrils, which are 

 small and round, are placed about a quarter of an inch from 

 the tip of the beak, and are about the eighth of an inch 

 apart from each other. Those singular receptacles, called 

 cheek-pouches, are possessed by the ornithorhynchus, and of 

 their use it will be necessary to speak hereafter. Its legs 

 are hairy above, and exceedingly short ; the hinder rather 

 shorter than the front pair j the feet have each five toes, con- 

 nected with each other by a strong membranous expansion ; 

 in the fore-feet, which are the largest and most powerful, the 

 web extends a little distance beyond the extremities of the 

 claws, whilst in the hinder-feet it attains only to the roots 

 of them. On the fore-feet are five claws, well adapted for 

 burrowing, being straight, strong, and sharp pointed ; the two 

 exterior ones somewhat shorter than the three middle ones. 

 The hind-feet have six claws, longer and more inclined to a 

 curved form than those of the fore-feet j the exterior toe and 

 claw are considerably shorter than the fore middle ones. The 

 fore-feet are naked both above and below ; but the hind-feet 

 are hairy above and naked below. The former, with their 

 membranous web, are, when expanded, four inches across, and 



