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 6 carpus,' 56 : the corre- 

 sponding mass in the hind limb is the 

 tarsus, 68. The terminal rays are the 

 digits, called f 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 c metacarpals ' in the hand, and ( meta- 

 tarsals ' in the foot. The other joints 

 are the ( phalanges,' ultimately distin- 

 guished as ( proximal,' ( 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 tf two ' in 

 Amphiuma, to ( three ' in Proteus, and 

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

 Axolotes. 



In the extinct Ichthyopterygia 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 



a ' 



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 

 6 humerus,' 53, and by the complex sca- 

 pular arch. The two antibrachial bones 

 retain the piscine shortness and breadth ; 

 skeleton of ichthyosaurus, with and the metacarpal series is less distinctly 



cast of spiral intestine. CLXIII. defined than ill SOlllC fishes. 



