HIGH SCHOOL ZOOLOGY. 127 



partly on the ptery go-palatine bar, and it supports the man- 

 tliblo, which in the adult is foru)ed of a single piece inclosed in 

 tlie lower horny beak. 



It is to be expected that the possession of the power of flight 

 should be associated with alteration of those parts of the 

 skeleton concerned, so that in addition to the rigidity of the 

 thorax conferred by the imnioval>ility of the dorsal vertebrae, 

 it is not surprising to find other conditions adapted to offer a 

 solid basis of resistance to the stroke of the wing, and protec- 

 tion to the delicate parts contained within the thorax. So the 

 true ribs are not only bound to each other by uncinate pro- 

 cesses, but their sternal ends, instead of being cartilaginous, 

 are bony. Again, the sternum does not only afford protection 

 to the thoracic organs by its great size, but by its keel offers 

 a large surface for the attachment of the muscles of flight. 

 "Although the scapula is small, the ventral parts of the shoulder- 

 girdle are both strong and connected with the sternum ; 

 especially is this true of the coracoid, through which the strain 

 of the wing stroke is chiefly transmitted to the trunk. The 

 chief peculiarity of the humerus is its strong crest for the 

 insertion of the muscles of flight, while the ulna differs from 

 the radius in its strong curvature, the convexity of which is 

 roughened by the attachments of the secondaries. It is the 

 wrist and hand that are mo.st peculiar, however, for we see only 

 two pi'oximal carpals, the distal carpals being fused with tlie 

 throe metacar[Kds into one perforated bone, while the three 

 fingers are independent. The second finger is the most im- 

 ]K)rtant, the third being rudimentary, while the first, which 

 supports the spurious wing when it is present, and like the 

 second is sometimes provided with a claw, is also short. 



Reference was made to the singular method of union of the 

 jjelvis to the trunk ; the other parts of the pelvic arch are 

 chiefly remarkable for their backward direction and for their 

 not meeting in a symphysis, except in some of the more reptilo- 



