170 



ANATOMY OF VERTEBRATES. 



the cnemion or leg. The mass of fibro-cartilage, in which 

 more or fewer ossicles are subsequently developed, interposed 

 between the antibrachium and terminal 

 rays, is the ' carpjus, 56 : the corre- 

 .' , ''; spionding mass in the hind limb is the 



tarsus, 68. The terminal rays are the 

 digits, called ' hand,' and ' fingers,' 69, 

 in the fore limb ; ' foot ' and ' toes ' in 

 the liind limb. The proximal joints of 

 these rays, being bound together in a 

 sheath of integument, are diiferentiated 

 as ' metacarpals ' in the hand, and ' meta- 

 tarsals ' in the foot. The other joints 

 are the ' phalanges,' ultimately distin- 

 guished as ' jiroximal,' ' middle,' ' distal ' 

 or ' ungual,' as usually supporting a claw 

 or nail. 



In the extinct Ganocepluda, and in the 

 few surviving ichthyomorphous or per- 

 ennibranchiate Batrachia, the simple 

 type of limb, as in fig. 101, B, is re- 

 tained ; only that the digital rays in- 

 crease in ninnber from the ' two ' in 

 '^j/i Amphiuma, to ' tluree ' in Proteus, and 



J^'i^l to 'four' in Menopoma, fig. 43, 57, and 



Axolotes. 



Inthe extinct Ichfhi/opferi/r/ia the digits 

 may be seven, eight, or nine in number, 

 and consist of numerous short joints — 

 a significant mark of piscine atfinitv : 

 they are bound together, but converge 

 towards a point : the joints are of a fiat- 

 tened angular form, and interlock with 

 those of the contiguous digit, the whole 

 forming a continuous, broad, slightly 

 flexible basis of support to the fin. The 

 essential distinction from the fin of the 

 fish is shown by the well developed 

 'humerus,' 5:1, and by the comjilcx sca- 

 pular arcli. The two autibrachial bones 

 retain the jiiscine shortness and breadth ; 

 and the metacarpal series is less distinctly 

 defined than in some fishes. 



«// 



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