CH. I] DISTRIBUTION OF CUCULID^. 35 



geographical range of its members and their structure ; 

 there is no confusion possible between the anteaters of 

 the Old World and those of the New, while, unlike though 

 they are outwardly, all the Edentata of the New World 

 form a natural assemblage; the Edentata of the Old 

 World form perhaps two natural assemblages of equal 

 value to the one of the OldJiVorld, but there is no hint of 

 any special resemblance between either and the New 

 World group. 



Though the Gallinaceae and the Edentates thus show 

 a decided relation between distribution and structure, the 

 same is not the case with other plentifully distributed 

 groups of birds. 



Distribution of the Cuckoos. 



The cuckoos will serve as an instance to the point. 

 This family has been investigated anatomically 1 to as 

 great an extent as the Gallinaceous birds ; and the mutual 

 affinities of the numerous genera is to some extent plain. 

 Fiirbringer is of opinion that the genus Phcmicophaes 

 represents more nearly than any other existing form the 

 primitive cuckoo. This is chiefly on account of the fact 

 that it possesses the complete muscle formula, none of the 

 typical muscles of the thigh being absent, and has a 

 syrinx constituted on what must be regarded as the 

 typical plan for birds, viz. the " tracheo-bronchial." The 

 remaining genera have diverged from this in two ways ; 

 either the accessory femoro-caudal muscle has disappeared, 

 i See Beddard, P.Z.S. 1886. 



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