288 THE ZOOLOGIST. 



Instead of the tarsus consisting as in all other beasts, and in 

 man of short bones only, the tarsal bones — the os calcis and 

 naviculare — are so much elongated as to merit the name of long 

 bones, and to add another segment to the limb. 



Passing now to other orders of beasts, we meet with curious 

 modifications of fingers and toes, according to the uses to which 

 they arc applied. In the most carnivorous of carnivorous 

 animals — cats, lions, and tigers— not only are the nails in the 

 form of exceedingly strong and curved sharp claws, but their 

 sharpness is maintained by the arrangement of the two last 

 phalanges of each digit. The joint between them is so formed 

 that the last readily rolls back on the last but one, and is 

 habitually retained in that rolled-back condition by an elastic 

 ligament. Claws thus conditioned are said to be retractile. 



The hand of the Bat is a very noteworthy organ. A Bat has 

 a thumb and four fingers. The thumb diverges widely from the 

 fingers, and is free, terminating in a strong hooked claw. The 

 four fingers are exceedingly long and slender, and also bound 

 together by a large membrane or web, which passes from the 

 little finger to the sides of the body. It is this extensive mem- 

 brane thus supported by delicate digits, like the rods of an 

 umbrella, which constitutes the Bat's wing. The Bat's feet, on 

 the contrary, serve little for locomotion, but the curved claws of 

 the five moderate digits act as hooks, by which the body is 

 habitually suspended, head downwards. 



In the Mole's hand we find the very opposite condition to 

 that of the hand of the Bat. All its component bones, instead 

 of being long and slender, are extremely short and thick, for the 

 Mole has to dig out the earth with extraordinary force and 

 rapidity, the little animal proceeding on its subterranean course 

 at such a rate, that it may be said almost to fly through the 

 earth, instead of, as the Bat, through the air. 



Progression through the water is generally accomplished in 

 another manner, namely, by lateral strokes of the hinder part of 

 the body. Everj'body knows that in most fishes the body ends 

 in a fin, which broadens out at the end of the tail from above 

 downwards. 



The Seal has but a very short tail, without any terminal 

 expansion. The feet, however, are so conditioned as to act in 

 the same way as would a vertically-expanded tail. The soles of 



