1877.] 



President's Address, 



441 



flying, creeping, and walking things, referable to so many orders of 

 plants and animals, and often of such gigantic proportions, that the palae- 

 ontologists of the States, with museums vastly larger than our own, are 

 at a loss for space to exhibit them. So common indeed are some species, 

 and so beautifully preserved, that I saw numbers of them, especially 

 insects, plants, and fishes, exposed for sale, and eagerly purchased by 

 travellers, with confectionery and fruit, at the stalls of the railway sta- 

 tions, from the eastern base of the Eocky Mountains all the way to 

 California. 



An examination of some of these fossils has brought to light the im- 

 portant fact that in North America there is no recognized break between 

 the Cretaceous and Tertiary beds. This is due to the interpolation of a 

 vast lignitic series the fossils of which furnish conflicting evidence. Con- 

 cerning this series Dr. Hayden, who has traced it over many hundred 

 miles, observes* that the character of its palseontological, as well as of 

 its strictly geological, results is such, that whether the entire group be 

 placed in the Lower Tertiary or Upper Cretaceous is unimportant, and 

 that the testimony of palaeontologists will probably always be as conflicting 

 as at present. 



Professor Marsh, of Yale College, Newhaven, one of the highest 

 authorities in America, has found that not even invertebrate fossils afford 

 a satisfactory solution of the difficulty. " These," he says, " throw little 

 light on the question and he is obliged to assume that "the line, if 

 line there be, must be drawn where the Dinosaurs and other Mesozoic 

 Vertebrates disappear, and are replaced by the Mammals, henceforth the 

 dominant type." 



This last passage I have taken from the lucid address of Professor 

 Marsh to the meeting of the American Association for the Advancement 

 of Science, held last autumn at Nashville, to which I must refer for an 

 exposition of the riches of the fossil Vertebrate fauna of these regions, of 

 the convincing proofs they afford of the doctrine of Evolution, and of 

 the light they throw on the introduction, succession, and dispersion of 

 existing organisms in the New "World. Among the suggestive obser- 

 vations with which this address abounds is another in reference to this 

 question of the disputed horizons of the Cretaceous and Eocene beds — 

 namely, its dependence on the relative value to be given to evidence 

 derived from plant and animal remains. He concludes that plants afford 

 unsatisfactory measure of geological periods as compared with animals 

 — a conclusion at which I had long ago arrived. We agree further that 

 a chief cause of this difference of value is the less complex organization 

 of plants, which hence furnish less evidence of the influences of envi- 

 roning conditions ; to which might be added the feeble conflict among 

 the higher members of the vegetable kingdom as compared with the 

 vertebrates, their stationary habits, and the duration of similar, if not 

 * Eeport of Geological Survey, 1874, p. 20. 



VOL. XXVI. 2 I 



