132 PLIOCENE CAVERN AT DOYEHOLES. [May I903, 



Mr. Beid's method of classifying the Pliocene strata by the flora and 

 mollusca, rather than by the mammalia, he remarked that it was 

 inapplicable not only to the Pliocene, but to the whole of the Tertiary 

 subdivisions. Prof- Gaudry proved, some 15 years ago, that the 

 mammalia were 'en pleine evolution' in the whole of the 

 Tertiary Era, while the rest of the animal kingdom had already 

 assumed those forms which they present in existing nature. In other 

 words, the mammalia alone had changed fast enough in the Tertiary 

 age to be of use in marking the time on the geological clock. With 

 regard to the vegetable kingdom, all geologists knew that the flora 

 had changed far more slowly than the fauna, and was therefore less 

 useful for classificatory purposes. The confusion imported into 

 geological classification by ignoring this fact was illustrated by 

 Heer's attribution of the flora of the North- American Cretaceous 

 Beds to the Miocene, because of its practical identity with the 

 Miocene flora of Switzerland. It took many years for this mistake to 

 be rectified by the discovery of the Cretaceous reptiles by Marsh and 

 Cope. The Author therefore attached no classificatory significance 

 to the few fragmentary plants referred to by Mr. Eeid. Nor did he 

 feel inclined to agree with Mr. Reid as to the specific importance of 

 the minute differences in the mollusca. He had tested the value of 

 Prof. Gaudry's appeal to the mammalia in the classification of the 

 Tertiary deposits, and found that it held good not only in Europe, 

 but in North and South America, and in Australia. The principles 

 laid down in his essay on the classification of the Tertiary Era 

 by means of the mammalia, published in the Quarterly Journal, 

 were applicable to the rest of the world. 



