THE DUCK-BILLED PLATYPUS. 239 



Singular conformation. 



extended, reaches about a quarter of an inch 

 into the beak. 



The beak itself is covered with a smooth black 

 skin, that extends some way beyond the bones, 

 both in front and laterally; and forms a moveable 

 lip, so strong, that when dried or hardened in 

 spirits, it seems to be quite rigid, but when mois- 

 tened, it is very pliant, and is probably a muscu- 

 lar structure. The under part of the beak has a 

 lip equally broad with the upper: this has a ser- 

 rated edge, wanting in the upper mandible, but 

 the serra3 are chiefly confined to the soft part. 



A curious transverse fold of the black skin by 

 which the beak is covered, projects all round, 

 exactly at that part where it has its origin. This 

 may probably be designed to prevent the beak 

 from being pushed farther into the soft mud, in 

 which prey may be concealed, than to this part. 

 The nerves that supply the beak nearly resemble 

 those of birds ; and the cavity of the skull has a 

 greater resemblance to that of a duck than a 

 quadruped. 



The organ of smell differs in some measure 

 from that both of birds and quadrupeds. The 

 external opening is placed near the end of the 

 beak, from whence two cavities, extending all 

 the way along the beak, are superadded to this 

 organ. The orifice of the eye is extremely small 

 in proportion to the size of the animal : and the 

 external opening of the ear is so minute as not 

 to be discovered without difficulty. 



