THE SKELETON OF THE FORE-LIMB 



25 



centrale may remain in the ideal condition. The bones 

 of the second row invariably show a fusion between 

 carpale IV. and carpale V. into the unciform bone. The 

 primitive five digits may persist, but an invariable 

 reduction takes place in the elements composing the 

 pollex, which consists of only three segments instead of 

 the ideal four. 



The immediate interest lies in the fact that these 

 conditions of minimal departure from the primitive type 

 are combined in the individual only within the limits 

 of the Primates and those other animals which we believe 

 to be immediately related to them (see Fig. 7). All 

 other Mammals, though retaining primitive features of 



FIG. 6. THE SKELETON OF 

 THE HAND OF A WATER 

 TORTOISE (Chelydea ser- 

 pentina). (AFTER GEGEN- 

 BAUR.) 



FIG. 7. THE CARPUS AS IT 

 EXISTS IN SOME PRI- 

 MATES. 



The os centrale is a separate 

 element. 



the fore-limb here and there, show in some other respects 

 wider departures from the ideal. 



Among the Primates we have skeletal fore-limb elements 

 so little altersd from the ideal type that the humerus 



