1897] NOTES AND COMMENTS 153 



evidence adduced by Dr W. B. Scott and others as to the separation 

 of North and South America cannot be overthrown by the con- 

 clusions drawn from one group of animals, more especially when an 

 alternative route of migration will explain the facts equally well, if 

 not indeed better. 



The Old World Edentate Mammals 



While it may be admitted that one swallow does not make a 

 summer, it cannot be contended that a single tooth is not amply 

 sufficient to prove the existence of the group of animals in the 

 country where it was found. And as Dr Wortman expressly states 

 that Calamodon europaeus — founded on a canine from the Swiss 

 siderolithes — is a member of the Ganodonta, there is ample evidence 

 of the existence of that group in Europe during the Eocene. Prob- 

 ably Dr Wortman is unaware how rare mammalian fossils are in 

 those deposits, and why he should make a point of their absence 

 from the later European Tertiaries passes our comprehension. With 

 regard to Africa, no Eocene or middle Tertiaries are known, and 

 consequently no arguments can be drawn one way or another. 

 Moreover, it is known that when the later South American ground- 

 sloths succeeded in entering the northern half of the New World 

 during the Pliocene, they flourished excellently well, and if their 

 ancestors reached the South from the North, it is difficult- to see why 

 the group should have immediately died off in the latter area. 



To our own thinking it is much more probable that the Eocene 

 Ganodonts of the northern hemisphere migrated southwards from 

 Europe to Africa, and eventually reached South America by that 

 route, as appears to have been the case with certain other groups of 

 mammals. This, of course, opens up the question whether the Old 

 World, so-called Edentates may not after all really belong to that 

 group. Without denying the possibility of this, it may be urged 

 that whereas the skulls and limb bones of the Ganodonta are 

 strikingly like those of the South American edentates, those of 

 Manis and Orycteropus are as strikingly unlike. If, therefore, 

 they belong to the same stock, they would appear to have diverged 

 before the Ganodonta assumed their characteristic type. But as 

 this was acquired in the early Eocene, the Edentate origin of 

 Orycteropus and Manis seems very problematical. At the same 

 time we have at present no other group in which to look for the 

 parentage of those strange creatures. 



New Light on the Ova of Vertebrata 



In the series of observations published by K. Mitsukuri, of Tokyo, 

 in the Journal of the College of Science of the Imperial University, 



