INTRODUCTION. 



counteracted by that of the flexor muscles, voluntarily or instinctively 

 exerted on a tendon of great size and power, running beneath the bones 

 of the toe, and inserted into the base of the claw -bone at its anterior part, 

 like the string of a pulley. In the very act of striking with violence, 

 these flexor muscles are strongly contracted, brace up the tendon, and 

 throw out the talon, which, when the act is over, returns into its sheath. 

 The following sketches, representing the claw protruded and retracted, 



will convey an idea of this exquisite piece of 

 mechanical contrivance (figs. 93, 94) : a, is 

 the claw-bone, or last phalangal bone, joined 

 to 6, the penultimate : c, is the oblique elastic 

 ligament, which rolls the claw-bone back, 

 assisted by tendons, d, of the extensor muscles 

 of the paw seated on the fore-arm, which also 

 share in this work ; the muscles relaxing in- 

 voluntarily when the flexors contract, and 

 resuming, on the relaxation of the flexors, their 

 habitual tension : e, is the strong tendon of the flexor muscles, bound 

 down at f t so as to be kept firmly along the under side of the bone. 



Thus far has been sketched a cursory outline of the modifications to 

 which the analogue of the human hand is subject ; and hitherto it has 

 preserved a resemblance, more or less faint, to its great prototype. But 

 its leading peculiarities have yet to be considered, as exhibited in what 

 may be termed the unclaviculated races those which not only have no 

 clavicle, but the construction of whose shoulder does not possibly admit 

 of it. Many animals, which have paws divided into rude fingers, and 

 which use the paw and arm with some degree of facility as the Bear, 

 the Coati, the Paradoxurus, the Hyaena either do not possess it, or 

 have it in the merest rudimentary condition : still they may 

 possess this bone ; its presence would not be an incongruity ; 

 and the anatomist can only determine the fact by inves- 

 tigation : but here the whole construction and use of the 

 limb forbid it, militate against it, and give the conviction, 

 that its presence would be an evil. With the impossibility 

 of the existence of the clavicle are associated two kinds of 

 limbs : the one, a hoofed, prop-like organ of progression ; 

 the other, a simple, paddle-like instrument, for propelling a 

 fish-like body through the water : the first is seen in the 

 Pachydermata and the Rurninantia ; the second, in the 

 Cetacea' and Seals. 



A sketch is annexed of the fore limb of the Elephant 

 (fig. 95). The general massiveness of the bones, and their almost per- 

 pendicular bearing on each other, are not now to be considered ; nor 



