THE INTERNAL SKELETON, 193 
Digits and Phalanges.—Except in one or two birds with defec- 
tive wings, such as the Apteryx and Cassowary (which have 
each but one digit in the hand), the pinion always includes some 
bones ( phalanges) belonging to the three digits which corre- 
spond with the three metacarpals already mentioned. 
The pollex consists of two small phalanges which support 
the “alula”*, The index is much larger than either of the 
other digits, and also consists of two phalanges which are rela- 
tively large, and occasionally there is a third phalanx. The 

Ricut Hanp or Ostricn. 
, Radiale, or radial carpal ossicle ; , ulnare, or ulnar carpal ossicle ; d,, 
ee phalanx of the index ‘digit which has three phalanges; d,, 
phalanx of third digit ; 7, ulna; 1, and m.,, metacarpals of second and 
third digits anchylosed together with that of the pollex; p, proximal 
phalanx. of pollex; 7, radius. 
third digit consists of but a single phalanx, except in the 
Ostrich, where there may be a second phalanx, and a small 
cartilage representing such a part has been found in a very 
young Duck. This third digit is applied to the outer *, or ulnar, 
side of the index digit. 
It is the pollex or the index, or both (as in the Ostrich), 
which alone, in existing birds, ever bears a claw. As we have 
* Se a ante, p. 154. 
| The wing being supposed to be completely extended. 
O 
