170 



ANATOMY OF VERTEBRATES. 



105 



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 ' carpus,' 56 : the corre- 

 sponding mass in the hind limb is the 

 tarsus, 08. The terminal rays are the 

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

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

 the hind limb. The proximal joints of 

 these rays, being bound together in a 

 sheath of integument, are differentiated 

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

 tarsals ' in the foot. The other joints 

 are the s phalanges,' ultimately distin- 

 guished as ' proximal,' i middle,' ' distal ' 

 or ' ungual,' as usually supporting a claw 

 or nail. 



In the extinct Ganocephala, 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 number from the ' two ' in 

 Amphiunia, to t three ' in Proteus, and 

 to ' four ' in Menopoma, fig. 43, 57, and 

 Axolotes. 



In the extinct Iclithyopterygia the digits 

 may be seven, eight, or nine in number, 

 and consist of numerous short joints — 

 a significant mark of piscine affinity: 

 they are bound together, but converge 

 towards a point : the joints are of a flat- 

 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,' 53, and by the complex sca- 

 pular arch. The two antebrachial bones 

 retain the piscine shortness and breadth ; 

 skeleton „f TcMkyosaurus, win, and the metacarpal series is less distinctly 

 cast of spiral intestine, cuou. defined than in some fishes. 



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