]()(5 i.v.vi/.N \i:\\' Y(n;i\ \cM)i:\n or sci i:\<'i:s 



as also the fact tliat the true correlation is so iiitimatoly related tn the 

 direction of mi<i"ratioii that the two ])rol)lenis must he settled together. 

 In view of the great and well merited reputation of Dr. .Vmeghino and 

 the immense array of data which he has marshalled in support of his 

 theories of correlation and phylogeny, it is not surprising that they should 

 find a very considerahle acceptance, not in -South America alone but else- 

 where. Few scientists indeed are disposed to accept his dei'ivation of the 

 horse family from eai'ly South American ancestors or of the various 

 families of Carnivoi'a from the same source, for in these and other cases 

 the evidence for northern ancestry is almost universally accepted as con- 

 vincing; but maiiy writers are willing to accept Ameghino's determina- 

 tion of the age of the Argentine formations, although more critical as to 

 his phylogenetic views. 



The two, however, must stand or fall together; and it is precisely be- 

 cause the Equidie, Procyonidae, etc., if their genei-ally accepted phylog- 

 enies be admitted, afford incontrovertible evidence against the validity 

 of Ameghino's correlations of the formations of the Argentine, tliat he 

 has been compelled to devise different phytogenies for these cases. Few 

 scientists will be willing to believe Ameghino's assertion that MerycMppns 

 and its successors in the equine phylum have nothing to do with the 

 Anchitheriinffi which they so closely resemble in teeth, in skull, in feet. 

 in all details of the skeleton, but must be derived from the South Amer- 

 ican NotohippidaB on the strength of a much more distant resemblance in 

 the second upper molar, unsupported by any near resemblance whatsoever 

 in the remaining teeth or in any points of construction of skull or of 

 skeleton. It is not my intention to present here any detailed refutation of 

 Dr. Ameghino's argument, but to point out that if the northern origin 

 of the EquidiE be accepted, the age of the Pampean and related forma- 

 tions must be far later than that he has assigned to them. The first ap- 

 pearance of true equines in South America is in the Pampean. The 

 three best-known genera are Et/uu-s, Uippidion and Onohippidioii. The 

 first might be regarded as of Palearctic origin ; the second and third have 

 no Old World predecessors, but may be directly derived from the North 

 American Pliohippus. They are. Iiowever, nnich larger and mori' pro- 

 gressive than PUohippuft, and in size, reduction of tlie lateral digits, etc., 

 are equivalent to E(jfius. We can hardly doul)t that tliey came to South 

 America from North America, nor can I see any practical alternative to 

 believing that Equns arrived by the same route. Now, the first appear- 

 ance of Equus in North America is at the base of the Pleistocene. In 

 Argentina, it first appears in the middle Pampean. The middle Pam- 

 pean cannot therefore be older ami is ])resumahly younger than Lower 



