328 



Vertebrata. 



fore-limb conforms to one type : articulating with the shoulder girdle 

 by its upper end is a long bone, the humerus; to its lower end 

 are attached two other long bones, the radius 

 and ulna, together forming the fore-arm; 

 at the proximinal end of the ulna there is 

 usually a process, the olecranon, which 

 projects over the radius. At the lower end 

 of the fore-arm is the carpus (wrist), 

 consisting, when completely developed, of 

 two transverse rows of small cartilages or 

 bones (carpals), three in the proximal, 

 radial e, intermedium, ulnar e, and 

 five in the distal row, one for each meta- 

 carpal : a small bone or cartilage (or 

 sometimes two) lies between these rows, 

 the centrale. To the carpus, which 

 undergoes many modifications, there are 

 attached five (or fewer, rarely more) series 

 of cartilaginous or bony pieces, of which 

 the proximal in each row is termed a 

 metacarpal, the others phalanges; 

 whilst the metacarpals usually lie close 

 together and are enclosed in a common skin, 

 the digits are, for the most part, free. 



The pelvic girdle, like the shoulder 

 girdle, is a paired or unpaired cartilaginous 

 or bony arch, affording an articulation for the 

 hind limbs. In Fish, it is independent of the 

 vertebral column; but in other Vertebrata, 

 it is almost invariably fused with one or more 

 vertebrae, the sacrals, on either side. Like 

 the shoulder girdle, each half is divisible, in all excepting Fish, into 

 a dorsal portion, above the acetabulum (the point of articulation 

 of the hind limb), the ilium, and a ventral piece which is, however, 

 usually divided into anterior and posterior parts, pubis and ischium; 

 the latter is usually articulated with the corresponding bone of the 

 other side. Ilium, ischium, and pubis are always separate bones in 

 young animals, and are connected by cartilage, of which, indeed, 

 the whole pelvis originally consists ; later, however, the three bones 

 more or less completely fuse with one another. The skeleton of 

 the hind limb corresponds closely with that of the fore limb, in 

 Fish and other Vertebrata ; in the latter, there is a femur (thigh- 

 bone), corresponding with the humerus; a shank corresponding 

 with the forearm, and consisting of a tibia and a fibula; a 

 tarsus (ankle), consisting of two rows of bones (tarsals) ; in 

 the proximal row, tibiale, intermedium, fibulare; five 



Fig. 270. Diagi-am of 

 the skeleton of the f o r e - 

 limb of a higher Verte- 

 brate. H humerus, B radius, 

 U ulna, u ulnare, i inter- 

 medium, r radiale, c centrale, 

 1 — 5 carpals ; / — Y first 

 to fifth digits. — Orig. 



