76i Mr. W. P. Py craft on the 



peckers to adapt themselves to changing environments, as 

 is indicated by their restriction, they are confined to the 

 Tropics ; yet they have contrived almost to encircle the 

 globe. That the American forms are the oldest seems 

 to be indicated by their arrival in this continent while they 

 were still plastic ; for there can be no doubt but that the 

 Rhamphastidse, Bucconidat, and Galbulidse are descendants 

 of some generalized, ancestral member of the Capitonidse. 

 An interesting confirmation of this view is that only the 

 American Capitonidse have the habit of turning the tail 

 over the back as in the Toucans. 



We may, then, regard the Jacamars, Barl)ets, and Puff- 

 birds as autochthonous types, having, like the Humming- 

 birds, been developed within the confines of the American 

 continent. A careful study of the various genera is now 

 needed to discover, if possible, the distribution of the least 

 and most highly specialized forms. The latter should occur 

 must frequently north of the Isthmus of Panama. 



The Passerit'ormes, which must now be considered, 

 supplement the evidence furnished by the Coraciiformes 

 as to the source of the avifauna of the New World, and 

 of Central America in particular, even though at present 

 gaps remain to be filled by further anatomical research. 



The Passeriformes, it must be remembered, are divisible 

 into four suborders — Eui'ylaemi, Oligomyodi, Traclieo- 

 phones, and Diaeromyodi. Of these, the Tracheophones 

 are peculiar to the New World. Whence did they come? 



The only clues to the solution of this question are such 

 as are to be furnished by structural characters. The most 

 striking of these is the syrinx, which has attained a high 

 degree of specialization, though its peculiarities are more 

 marked in some species than in others — a fact of no little 

 importance in tracing descent. 



The syrinx, however, merely furnishes the measure of 

 agreement between the several members of the family, 

 which, both osteologically and myologically, shows affinities 

 with the Tyrannidae and Pittidse, on the one hand, and the 

 Eurvlfcmidpe. on the other. Thus the cxclusivelv American 



