CH. l] FOSSIL CUCKOOS. 37 



between the genera of the different parts of the world. 

 So far as our knowledge of living cuckoos goes the facts 

 have no significance in this connection. Presuming with 

 Wallace that they originated in the tropics of the Old 

 World and thence spread to the New World we have the 

 remarkable fact that in the lengthy journey to South 

 America the two main types already differentiated before 

 migration took place, have been equally successful in 

 colonisation, and have advanced equally far. Fiirbringer 

 holds, and with some justice, that a country inhabited by 

 the oldest form of the group in question is more likely 

 to be its original habitat than elsewhere. In this case 

 Wallace's view that the cuckoos sprang into existence in 

 the Oriental region is supported. But quite recently the 

 whole matter has been put in a rather clearer light. 

 Milne-Edwards has found 1 the remains of a cuckoo which 

 he has relegated to a new genus and which he is unable 

 to distinguish from the living Phcenicophaes. In this case 

 Flirbringer's belief that Phcenicophaes is the nearest 

 approach to the archetypal cuckoo is to some extent 

 justified ; and we have a family formerly of wide range, 

 which is a further proof that it is an ancient form. 

 Moreover if we can now assume that the parent stock 

 of the cuckoos was differentiated in Europe and thence 

 spread over the New as well as the Old World, the 

 difficulties in the way are at least rendered less. 



We shall now indicate briefly the distribution of a few 

 of the principal groups of animals. The mammals and 



1 Comptes Rendus, 1894. 



