152 NATURAL SCIENCE [September 



The South American Edentate Mammals 



Having satisfactorily demonstrated the ancestral position of 

 the Ganodonta to the modern American Edentata, Dr Wortman 

 goes on to observe that if this be true, " it follows that all the 

 South American edentates must have been derived from the 

 North American Ganodonta, since their earliest appearance in 

 South America does not antedate the Santa Cruz epoch. In this 

 formation they appear suddenly in great numbers and variety, 

 without apparently any announcement in the older Pyrothcrium 

 deposits. This fact in itself would seem to indicate that they 

 were migrants from another region, and while we are as yet unable 

 to place these deposits in the time-scale with accuracy, it is yet 

 highly probable that the Santa Cruz beds are not older than our 

 North American Oligocene. In North America the Ganodonta 

 appear in the very earliest Puerco deposits, and continue without 

 interruption into the Bridger, where they disappear. No evidences 

 of them have up to date been detected in the Uinta or White 

 River beds. 



" Now it is currently believed by geologists that no land con- 

 nection existed between North and South America from the close of 

 the Cretaceous to the close of the Miocene, when an extensive land 

 bridge was formed. I am not familiar with the geological evidence 

 upon which the conclusion rests, but if one is permitted to judge 

 from the subjoined statements of Mr F. C. Nicholas, it is at the 

 very least open to question. It is, of course, possible that the 

 Ganodonta may have reached South America by way of Europe, 

 Africa, and Antarctica, but on the whole it seems infinitely more 

 probable that there was a land bridge of short duration during 

 Eocene time between North and South America, and that they 

 reached their destination in this way, than by the questionable and 

 circuitous route just mentioned. If they gained entrance into 

 South America by the European- African route, it seems indeed 

 strange that they should have left no remains in the later Tertiaries 

 of Europe. "With the exception of a single specimen of Calamodon 

 Europaeus, from deposits corresponding with the Wasatch in age, all 

 traces of the American Edentata are absent in Europe, Asia and 

 Africa." 



To the first paragraph in this ([notation no exception can be 

 taken. With regard to the second, we have not the pleasure of 

 being acquainted, either personally or by his writings, with Mr F. 

 C. Nicholas, who may be a most excellent person, bnt the rambling 

 extracts from a letter of his, which Dr Wortman prints in a foot- 

 note, can scarcely affect the problem of a land connection between 

 the two Americas in early Tertiary times. Apart from this, the . 



