890 



SCIENCE 



[N. S. Vol. XXX. No. 781 



isolate and identify the toxic elements in 

 them. 



SPECIAL ARTICLES 



THE GEOLOGICAL AND GEOGRAPHICAL DISTRIBUTION 

 OF SOME PLEISTOCENE MAMMALS 



Some months ago Professor Henry F. Os- 

 born, of the American Museum of Natural 

 History, published' an important paper en- 

 titled " Cenozoic Mammal Horizons of West- 

 ern North America." Having had occasion 

 recently to consider some phases of the Pleis- 

 tocene I have examined with interest the part 

 of Professor Osborn's paper devoted to this 

 period. 



Professor Osborn has been giving attention 

 ■ to Tertiary history and correlation for many 

 years. In 1900^ he published his " Correla- 

 tion betvsfsen Tertiary Mammal Horizons of 

 Europe and America," in vrhich he devoted 

 eleven pages to a consideration of the Pleisto- 

 cene. In connection with this he issued a 

 " Third Trial Sheet," in the preparation of 

 which he had the assistance of several Euro- 

 pean geologists and paleontologists. The paper 

 and the trial sheet dealt more especially with 

 European history. The paper of 1909, put 

 forth after nine years' further investigation 

 on the part of Professor Osborn, during 

 which time numerous other paleontologists 

 and geologists bad occupied themselves with 

 Pleistocene studies, presents more fully the 

 American side of the problems. 



In Professor Osborn's treatise of 1900 he 

 and his collaborators recognized fully the work 

 that had been done by geologists in their de- 

 termination of the existence, in Europe, of 

 more than one sheet of glacial accumulations 

 and one or more interglacial deposits. In the 

 communication of 1909, on the contrary. Pro- 

 fessor Osborn makes no mention of the great 

 advances that have been made within recent 

 years in the knowledge of the Glacial epoch 

 in North America, resulting in the discovery 

 of four or five distinct glacial sheets and a 

 corresponding number of interglacial deposits 

 of soils, peat beds, gravels and sands, with 

 their organic contents. His bibliography of 



' Bull. U. S. Geol. Surv., 361, pp. 1-90. 



' Ann. N. Y. Acad. Sci., XIII., pp. 1-64. 



the Pleistocene (pp. 17, 18) contains no refer- 

 ences to such authors as Bain, Calvin, Oham- 

 berlin, Dawson, Leverett, Lewis, Salisbury, 

 Tyrrell and others whose works have been of 

 the highest value in the solution of many 

 problems connected with Pleistocene history. 

 And it may be affirmed with confidence that 

 without giving due consideration to glacial 

 geology no correct solution of the paleontology 

 of the Pleistocene is possible. 



It appears to have been Professor Osborn's 

 intention to divide the Pleistocene into the 

 Lower, or Preglacial; the Middle, or Glacial, 

 and the Upper, or Postglacial; although he 

 does not mention the last division. We need 

 not here discuss the propriety of recognizing 

 a preglacial stage of a period that has little 

 or nothing to distinguish it from the Pliocene, 

 except the presence of glaciers. On page 8Y 

 of Bulletin 361 is a table showing the approxi- 

 mate times of appearance and disappearance 

 of certain important genera of mammals. It 

 is an unfavorable comment on our knowledge 

 of the Pleistocene, when all that can be said 

 of six important genera is that they disap- 

 peared at some time during the Glacial period. 

 It is my belief that the history of some of the 

 interesting animals concerned can be deter- 

 mined somewhat more accurately. A begin- 

 ning will be made with Equus, the horses, a 

 genus which Osborn says disappeared from' 

 North America during the " upper mid-Pleis,- 

 tocene," a time which unfortunately he does 

 not limit either downward or upward. 



If now we indicate on a map all of. the 

 apparently authentic finds of fossil horses in 

 the United States east of the great plains, we 

 learn that, starting in New Jersey, one series 

 of localities arranges itself along the Atlantic 

 and the Gulf coasts, while the other, with a 

 few important exceptions, follows an irregular 

 line through Pennsylvania, Ohio, Indiana, 

 Kentucky, Illinois, Missouri, Iowa and South 

 Dakota. A comparison with a map showing 

 the glaciated region of the country indicates 

 that the localities of the last series (barring 

 the few exceptions) are situated close to the 

 southern border of the drift-covered area. 



The earliest discovery of fossil horse re- 



