XIV. 



bones are fixed in this position, but in a few, as in Man, a free 

 movement of crossing and uncrossing technically known as pro- 

 nation and supination is allowed. In most Quadrupeds the 

 ulna is much reduced in size, and the radius, especially at its 

 upper end, correspondingly increased, so that the articular surface 

 of the latter extends across the entire anterior surface of the 

 humerus, and thus the bones become anterior and posterior, 

 instead of external and internal. 



Manns, The skeleton of the terminal section of the anterior 

 limb consists of three divisions : (1) the carpus, a group of 

 small, more or less rounded or angular bones, with flattened 

 surfaces contiguous to one another, which, though articulating by 

 synovial joints, that is joints enclosing a capsule which secretes a 

 lubricating fluid, have, nevertheless, scarcely any motion between 

 them ; (2) the metacarpus, a series of bones, placed side by side, 

 and with their proximal ends articulating by almost immovable 

 joints with the carpus; and (3) the plialcinyvs, or bones of the 

 digits proper, which are usually three in number to each digit, 

 and articulate to one another, and the first to the distal end of 

 the corresponding metacarpal bone, by freely movable hinge- 

 joints. 



Carpiis. The mammalian carpus consists of two transverse 

 series of bones, of which the upper or proximal, series contains 

 three bones, that on the radial side, from which side all these 

 bones are counted, being known as the scaphoid, that in the 

 middle the lunar, and that on the left the cuneiform bone ; the 

 lower or distal series contains five bones, of which the two outer 

 are always united into a single bone, and receive a common name ; 

 these have been respectively termed the trapezium, Irapezoid, 

 magnum, and unciform ; between these two series a single bone, 

 the central, may or may not be present. Two additional bones are 

 generally developed in the tendons of the flexor muscles, one on 

 each side of the carpus, which may be called the radial and ulna 

 sesamoid bones ; the latter of these, which is the more constant, 

 and generally the larger, has received the distinctive title of the 

 pisiform bone. 



Metacarpus and Phalanges. The metacarpal bones are never 

 more than five in number, nor are the digits which they assist in 

 supporting ; they are described numerically as first, second, etc. 

 The digits have each a distinguishing name, the pollex (thumb), 

 index, medius, annulus, and minimus. One or more of these 

 may be in a rudimentary condition, or altogether suppressed, 

 and where only one is absent it is generally the pollex. No 

 Mammals, except the CETACEA, have more than three phalanges 

 to each digit, while in the pollex one of the three is constantly 

 absent. The terminal phalanges are usually specially modified 

 to support the nail, claw, or hoof, and are termed uncrual 

 phalanges. Distinguishing terms ai*e applied to the mode of 



