314 ANNAL>^ M:\V YORK ACADEMY OF SCIENCES 



throuo-h Anchitheriinn ; the American Miocene series does not come to 

 an end with Merychippus, but this genus gives rise through numerous 

 intermediate species to Protohippus, Pliokippus and Ilipparion. Ilip- 

 pidion is not a descendant of Ilipparion but of Pliohippus. There is, it 

 is true, a considerable gap between Ilipparion gracile and Equus, this 

 species being too specialized in tooth pattern and its lateral digits ex- 

 ceptionally heavy ; but most of the Amerifcaii hipparions are simpler and 

 less aberrant in tooth pattern and the shafts of their lateral digits reduced 

 often to mere threads. The proximal splints in these forms are very 

 nearly as much reduced as they are in Equus; the gap which Doctor 

 Gadow declares has been "slurred over" lies simply in the fact that no 

 specimens have yet been found in which the shafts of the lateral digits 

 are discontinuous but the distal rudiments preserved. Anyone familiar 

 with the difficulty of securing proof of this condition in a fossil species, 

 and with the imperfection of our record of the Pliocene Equida% will 

 hardly consider this as a serious gap. Certainly, it is trifling in com- 

 parison with the gaps in any of the other mammalian phyla which Doctor 

 Gadow accepts without difficulty. As for the derivation of Equus from 

 primitive species of Ilipparion rather than of Protohippus, my opinion 

 to that effect rests upon intensive studies of Miocene Equidae undertaken 

 for Professor Osborn's monogi'aph of the Evolution of the Horse (in 

 preparation) and I do not think it fitting to publisli the evidence in its 

 support at present. 



The sirenians, Dr. Gadow tells us, afford strong support of the theory 

 of a transatlantic bridge, the earliest being known from the Eocene of 

 Jamaica and Egypt, etc. They would, undoubtedly, if there were suf- 

 ficient reason to believe that they were absent from the more northerly 

 parts of the jSTorth-Atlantic-Arctic shores during the early Tertiary. But 

 there is none whatsoever; the North Atlantic coasts either extended dur- 

 ing the Tertiary beyond their present limits to or towards the continental 

 shelf, or else their marine and littoral deposits have been destroyed by 

 glaciation; at all events none remain above water worth mentioning 

 from New Jersey on one side around to the British Isles on the other. 

 That no littoral vertebrates should be known where there are no littoral 

 deposits is not sui-prising ; yet it is upon this worthless negative evidence 

 that the "strong support" rests. 



I have limited myself in the foregoing criticism to noting a few points 

 in regard to fossil mammals. Dr. Scharff^s book is far too extensive for 

 any detailed criticism here, even within these limits. I can note only 

 that, while highly instructive as well as entertaining, it is far from being 

 either accurate or fair in its treatment of the geological aspects of the 



