iS94. THE LA PLATA MUSEUM. 123 



animals provided with three functional toes to each foot) with 

 the lower Eocene of Europe, while the Parana, Monte Hermoso, 

 and other intermediate beds are assigned to the Oligocene and 

 Miocene, and the Pampean deposits identified with the Pliocene. 

 Now the fact that in the reputed lower Eocene beds we 

 meet with animals having a foot as specialised as is that of 

 Pyoterothennni, serves, to my mind, at least, to show the utter un- 

 tenability of the hypothesis in question. We know that in the 

 lower Eocene of both Europe and North America the Ungulates 

 were all five-toed animals with brachydont, and generally 

 tritubercular teeth; and if the South American Ungulates with feet of 

 the Pyoterothevium type, hypsodont molars like those of Nesodon, or tusks 

 of the length of those of Astyapotherium, were also of lower Eocene age, 

 it would involve the existence of a mammalian fauna like that of the 

 Puerco Eocene and London Clay in some part of the world during the 

 Cretaceous epoch, from which the Patagonian Ungulates had originated. 

 Of the existence of such a fauna there is, I need scarcely say, not only 

 a total lack of positive proof, but likewise very strong evidence to the 

 contrary. Then, again, the existence of a member of the existing genus 

 Dasypus (Zaedius) in the Santa Cruz beds renders it impossible to 

 regard them as of lower Eocene age. 



Moreover, in my forthcoming memoir on the fossil Cetaceans in 



the La Plata Museum, I have called attention to the circumstance 



that in one part of Patagonia there occurs a bed yielding Cetacean 



remains which appears to underlie the Santa Cruz deposits. Now 



this Cetacean bed most certainly is not of lower Eocene age, and is, 



indeed, probably Miocene, an identification which, if established, will 



at once overthrow the Eocene, or, indeed, Oligocene hypothesis of the 



Patagonian beds. Apart from this evidence, I am, however, quite 



convinced that the Patagonian Ungulates, owing to the speciahsation 



of the feet in some cases and of the teeth in others, are not lower 



Eocene, or even Eocene at all, but are far more probably of Miocene 



age. The correlation of some of the beds lying between the Santa 



Cruz and Pampean deposits with the European Oligocene and 



Miocene likewise will not bear critical observation, and can, 



indeed, only be maintained by the creation of species or genera 



which have no existence save in the minds of their founders. For 



instance, 1 find it impossible to distinguish specifically the remains of 



Typotherimn found in the reputed Miocene strata of Monte Hermoso 



from those of the typical Pampean form, while, as I have already 



shown, the so-called Hipphaplus of the supposed Oligocene Parana 



deposits is nothing more than a species of the Pampean genus 



Hippidium ; and if we are to have Oligocene strata with a genus so 



close to Equns as to be doubtfully distinct therefrom, what possible 



grounds can there be for correlating them with the horizon so-named 



in Europe ? I can believe, indeed, in the late survival of a 



generalised genus, but I utterly refuse to credit the occurrence of a 



