iv.] SKELETON OF UPPER LIMB. 175 



Aye ; or thick, as in the Great Armadillo. The digits may be 

 enormously long, as in the Bats ; or short, as in the Land 

 Tortoises. They may be very imperfectly developed, as in 

 Birds. 



They may be so united by dense tissue as to be quite 

 incapable of separate motion, as in the Cetaceans. The 



S 

 FIG. 149. RIGHT HAND OF OSTRICH. 



f ', radial carpal ossicle ; c 2 , ulnar carpal ossicle ; d" 2 , proximal phalanx of the 

 index digit which has three phalanges ; o? 3 , phalanx of third digit ; /, ulna ; 

 in 2 and in 3 , metacarpals of second and third digits anchylosed together and 

 with that of the pollex ; /, proximal phalanx of pollex ; r, radius. 



bones of the fingers or phalanges of man are the same in 

 number as in other Mammals with the exception of the 

 Cetacea. In distinctness they also agree with most, but it 

 is possible for the proximal row of phalanges to become 

 anchylosed to the metacarpals, as is the case in the Three- 

 toed Sloth. 



The phalanges, instead of decreasing in length, distad, 1 as in 

 man, may so increase as in the three ulnar digits of Dasypus 

 villosus. A terminal phalanx of a digit may far exceed in 

 length its two proximal phalanges, as is the case in the 

 middle finger of Priodontes, and in the three middle digits of 

 Perameles. 



The number of phalanges may be much greater than in 

 man, e.g. as many as fourteen, in the third digit of Glo- 

 biocephalus. Often in Reptiles the number of phalanges 

 increases from two in the pollex to five in the fourth digit, as 

 in the Monitor. The abortive hand of Birds at its best has but 



1 As we proceed from above downwards to the fingers' ends. 



