ELEMENTARY SKETCH OF THE OSTEOLOGY OF BIRDS. 21 



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and they are so articulated together, and with the humerus, as 

 to admit of scarcely any rotation one or the other. 



The carpus* which corresponds to the human wrist, is not 

 composed of two rows of small bones as in the latter, but consists 

 of only two bones placed side by side, one of which (radiale), 

 articulates with the radius, and the other \iilnare) with the ulna. 



The manust (plate I., m. & ph. 1, 2, 3) of the bird generally 

 has three digits, which correspond to the pollex| and the second 

 and third digits of the human hand (fore and middle fingers) ; the 

 metacarpal bones of these digits are usually anchylosed together. 

 The metacarpal bone of the pollex (m. 1) is usually much 

 shorter than either of the metacarpals of the other two dicrits. 

 The metacarpal of the second digit (m. 2) is stout and straight, 

 while that of the third (m. 3) is curved and slender; a vacant 

 space is generally left between the metacarpals ; but this may be 

 filled up with bony matter. The pollex has usually two phalanges, 

 § the last of which may be curved and sheathed with horn. || 

 The second digit has typically three phalanges, but frequently as 

 in the figure fph. 2) only two are developed. The third ditrit 

 never has more than two phalanges, and frequently, as in the 

 figure (ph. 3), has only one. 



In some of the Ratitse (Apteryx and Casuarius) there is but 

 one complete digit in the manus, which probably corresponds to 

 the second digit of man. This digit is incased in horn and forms 

 a claw. In the Ostrich the second digit is likewise terminated 

 by a claw, but in no bird is the third digit so modified. 



Pelvis.^ — The position of the pelvis of the bird is shown in 

 the figured skeleton (pi. I., pi.), while the details of the conjoint 

 bones, which form this part of the skeleton, are shown in figures 

 4 and 5 of plate III. Like that of a mammal or reptile, the 

 pelvis of a bird consists of three distinct pairs of bones, viz., 

 the ilium'^* (il,),, the ischium^\^\ (is.), and the pubisXX (pb.), the 

 three united bones of either side being united to the verte- 

 brae of the sacrum, and adjacent regions (sm.) The ilia (il.) 

 of the avian pelvis are remarkable for their great antero-pos- 

 terior extension, and for uniting with the whole length of the 

 edges of the sacrum (sm.) Superiorly each ilium forms a 



* Carpus, from Kapiros, the wrist. 

 f Manus, the hand. 

 J Pollex, the thumb. 



§ Phalanges, (buXav^ a row — applied to the bones of the fingers and toes. 

 II In the figured skeleton the phalanges of the pollex are wanting. 

 ■[[ Pelvis, a basin, — applied to the bony arch with which the hind limbs of the Ver- 

 tebrata articulate. 



** Ilium, from ilia, the flanks. The haunch bone — so called from supporting the 



ft Ischium, from icxiov the hip. 



XX Pubis, from puhes, hair, so called because this borne underlies the hair of the 

 groin. (See further as to the Pubis, the P. S. p. 28J 



