MAMMALIAN ORDERS. 



289 



Pinnigrades (Walrus, Seal-tribe) both fore and hind feet are short, 

 and expanded into broad, webbed paddles for swimming, fig. 173, 

 the hinder ones being fettered by continuation of integument to 

 the tail, fig. 172. In the Plantigrades (Bear-tribe) the whole or 

 nearly the whole of the hind foot, fig. 174, forms a sole, and rests 



174 



c b 



riantigrade foot, hind limbj Bear. 



on the ground. In the Dlgitigrades (Cat-tribe, Dog-tribe, &c.) only 

 the toes touch the ground, the heel, cZ, being much raised, fig. 175. 



It has been usual to place the 175 



Plantigrades at the head of the '^W 



Carnivora, apparently because ^mV' r":;^ 



the higher order, Quadrumana, is ^^ ^%\ llrV\ 



plantigrade ; but the affinities of c^^ \V r v 



the Bear, as evidenced by inter- ^^^ \*^ /' 



nal structure, e. g. the renal and M\\ \ # // ^ 



genital organs, are closer to the ^IM^^) f 



Seal-tribe ; the broader and flat- tt ^Pir ' 



ter pentadactyle foot of the planti- <? - "flEi^r^'' 



grade is nearer in form to the ^ m^^r^^ ^ 



flipper of the Seal than is the H ) }J\) 



more perfect digitigrade, retrac- m I --f-y * 



tile-clawed, long and narrow hind ^.^^^ 11 I I 'i '^ 



foot of the feline quadruped, /^^^^^-■^ii k I \ 



which is the highest and most \W^^^j^\^f\^'^mA\ 



typical of the Carnivora. The '"V \Qr' 'ffj^i '1/ 



oldest known species of the order ""' "^^'^fc^ ^^^^ 



are of eocene tertiary date. v^-' ^ \, 



/. . 1 • 1 • Digitigrade foot, liind limb. Lion. 



The next perfection which is 

 superinduced upon the unguiculate limb is such a modification 



VOL. II. u 



