Professor 0. C. Marsh — Origin of Mammals. 13 



by at least one geologist of repute, that the east-and-west section of 

 the Baltic, together with the Sounds between the Danish islands, 

 are in fact very recent features geologically speaking. It is very 

 probable that when the Drift was distributed they did not exist 

 at all, at all events in the place where we now find them, but that 

 a continuous land surface connected Scania and Denmark with 

 Mecklenburg and Poraerania. 



I hope to discuss this issue and the consequences dependent on it 

 on a later occasion. The present paper concludes what I have to 

 say in criticism of the Glacial theory as applied to Norway and 

 Sweden, and until some one tries to answer what I have urged 

 I shall conclude that it is unanswerable, which is not an unsound 

 position for a heretic to take. 



T 



III. — The Origin of Mammals.^ 

 By Professor 0. C. Marsh, M.A., Ph.D., LL.D., F.G.S. ; 



HE question as to the origin of mammals is not new, but one of 

 a series of similar nature and difficulty. The origin of Birds, 

 of Eeptiles, of Amphibians, and of Fishes really precede it, and offer 

 less difficulties in solution. The answer to each, in my opinion, 

 belongs to the future, and how far it may profitably be sought in the 

 present limited state of our knowledge is a fair question in itself. 



Too often in the past, a discussion on the origin of Mammals has 

 seemed a little like the long philosophico-theological controversies 

 in the Middle Ages about the exact position of the soul in the human 

 body. No conclusion was reached, because, for one reason, there 

 were no facts in the case that could settle the question, while the 

 methods of investigation were not adapted to ensure a satisfactory 

 answer. This discussion has been on a much higher plane, and 

 we have bad an admirable presentation of one side of the case. 

 I cannot, however, quite agree as to the value of the facts and 

 theories that have been presented, and shall consider the question 

 from another point of view. 



The Mammals, as we know them to-day, are classed by themselves, 

 yet contain such diverse groups that it may fairly be regarded an 

 open question whether all have a common origin. The attempt to 

 ascertain whence they came is likely to bring out indications that 

 they may have had several sources of origin, and this, if so, may help 

 to explain the great diversity among them. 



It is of course evident that some of the most characteristic features 

 of recent mammals — for example, the hairy covering, the circulatory 

 system, and the milk glands — cannot be used in a comparison with 

 fossil forms. The osseous structure only is now available in the 

 early mammals and other vertebrates, and in this alone points of 

 resemblance must be found if different groups are connected 

 genetically. 



^ Remarks in tbe general discussion on the Origin of Mammals at the International 

 Congress of Zoology, Cambridge, England, August 25, 1898. 



