320 THE HAKMONIES OF NATURE. 



waters, we find the construction of the extremities equally well- 

 fitted for swimming. Thus .the legs of the otter are short 

 and strong, but so loosely articulated as to turn in every direc- 

 tion while swimming the feet broad, to act as paddles, and 

 the toes connected by a complete web. Provided with such excel- 

 lent oars, which are moreover assisted by the flat and broad 

 tail and the elongated and much-flattened body, the otter is 

 able to breast the stream for hours together raising its head 

 from time to time out of the water, to draw breath or to look 

 about him. 



The amphibious beaver and the extraordinary inullingong, or 

 duck-billed platypus, whose existence as a mammalian was long 

 a matter of doubt, likewise show by the formation of their 

 extremities how well their peculiar wants have been provided 

 for. In its webbed hind-feet the former possesses most excellent 

 rudders, while the unw ebbed toes of its forefeet are no less 

 admirably adapted for seizing the branches and trunks of trees, 

 which it uses for the construction of its huts, or on whose bark it 

 feeds. 



In the mullingong, on the contrary, we find the forefeet 

 provided with a web, which not only unites and fills the inter- 

 spaces of the long toes, but even extends beyond the ex- 

 tremities of the claws ; while the web of the short and narrow 

 hind-foot, terminating at the base of the claws, is far less deve- 

 loped. But as the mullingong is not only an aquatic but also a 

 burrowing animal, the large web of the forefeet, which else 

 would have been very much in the way, is loose, so a to fall 

 back when its possessor is scratching the earth ; and thus, by a 

 most ingenious contrivance, the same organ serves equally well 

 as an oar and as a shovel. 



While in all these cases the limbs are most admirably fitted 

 for an aquatic or amphibious life, those of the bats are no less 

 beautifully adapted for aerial locomotion. For here the slender 

 delicate bones of the forearm, and particularly those of all the 

 fingers excepting the thumb, are extremly elongated, so as to serve 

 like the frame of an umbrella for the expansion of an enormous 

 wing or thin membrane, which reaches also to the hind-legs, and 

 from them to the tail. It is evident that with forefeet like 

 these, the walking or creeping movements of the bat must be 

 exceedingly awkward, and that the strange creature is far from 



