FORE-LIMB. 



493 



In stating the number of the carpal bones the pisiform ,is 

 generally included, so that a carpus with a centrale is said to con- 

 sist of nine bones, without a centrale of eight. 



The radial and ulnar sesamoids have been regarded as vestiges of extra 

 digits, viz. of a prepollex and postminimus respectively. Another view is 

 that the radial sesamoid is in reality the radiale, the scaphoid being a 

 second centrale. It cannot be said that these views are generally held, but 

 it may be noted that occasionally the radial sesamoid is double and 

 bears a nail-line structure (Pedetes caffer). 



It frequently happens that when the digits are reduced in 

 number, the persisting metacarpals and metatarsals, to which 

 the single name metapodium may for convenience' sake be given, 

 are elongated, or even fused together to form the so-called 

 cannon bone. 



FiO. 262. — Skeleton of the manus of a oran?, 6 dog, c pig, d ox, e tapir, / horse (from Claus). 

 A scaphoid ; H lunar : C cuneiform ; D traper.um ; E trapezoid ; P magnum ; G unci- 

 form ; F pisiform ; C centrale ; M metacarpus ; 1-5 digits numbered. 



The number of phalanges characteristic of the Mammalia has 

 already been given (p. 480). 



The ungual phalanges are the terminal phalanges which bear 

 the claws, nails, or hoofs. A plantigrade animal is one which 

 places the whole of the lower surface of the manus (carpus, meta- 

 carpus, phalanges) or pes on the ground in walking. The term 

 digitigrade is applied when the two distal phalanges only are 

 applied to the ground, the first phalanx and the metapodia being 

 vertical. When the last phalanx and hoof alone carry the 

 weight the animal is said to be unguligrade. There are also 



