288 VERTEBRATE ZOOLOGY 



nate birds. By considering them as an appendix to the Ratitae we 

 shall avoid doing violence to the opinions of either faction. 



The home of the tinamous (Fig. 157, A), of which there are about 

 forty species, is the New World, their range being from the extreme 

 lower end of South America to Mexico. Though they bear a strong 

 superficial resemblance to gallinaceous birds, especially the partridges, 

 it is believed by some authorities that they are more fundamentally 

 related to the Ratitae, though they are able to fly. Their wings are 

 short and rounded, but the keel of the sternum is well developed and 

 the pectoral musculature is large in size. The tail feathers are re- 

 duced in size, even rudimentary in some species. They are strong, 

 swift runners and are reluctant to resort to real flight; nevertheless 

 when they do fly they make a fairly good job of it for short distances. 

 With a great whirring of wings and extraordinary effort they rise to 

 fifty or sixty yards above the ground and then with expanded wings 

 glide slowly down to the ground, covering distances of about a thou- 

 sand yards, which may be repeated several times if necessary. 



It seems likely that the tinamous represent a condition intermedi- 

 ate between the flying birds proper and the running or flightless birds, 

 for they possess characters that relate them to both groups. Some 

 authorities beUeve that the ostriches and their kin have probably 

 been derived from an early group of rather weak fliers that is now 

 represented by the modern tinamous. 



Keeled oe Flying Birds (Neornithes Carinat^) 



Nearly twelve thousand species of modern birds belong to this 

 great division, as compared with a dozen or so species of all other 

 living birds. The study of birds has grown into the highly specialized 

 science of Ornithology, and a very large number of both professional 

 and amateur naturalists and bird lovers have been engaged in adding 

 to the already voluminous annals of bird lore and pseudo-lore. A 

 vast literature dealing with the habits, distribution, migrations, and 

 adaptations of birds has accumulated, much of which is worthless, be- 

 cause exaggerated, inaccurate, and superficial. But the authentic 

 literature on all phases of bird life is so voluminous that no one but a 

 specialist can hope to keep abreast of it. 



The classification of the carinate birds, though elaborate, is in a 

 fairly satisfactory condition. Only in a few minor points is there 

 radical disagreement among authorities. Among the most acceptable 



