208 TERTIARY TIMES. 



under their shields ; macrauchenes, or llama-forms, bulky as 

 camels; liymnodons, or hyaenas, stronger than tigers ; dipro- 

 todons, or kangaroos, heavier than oxen ; and colossoclieles, 

 or carapaced turtles, full fourteen feet in diameter, are but 

 random instances of the colossal structures that have been 

 exhumed from the sediments of the tertiary epoch. In 

 this respect the fauna of the period seems to corroborate 

 the idea that there is a culminating point in the life of 

 orders, as there is in the life of individuals a period 

 when they attain their maximum development in numbers, 

 variety, and magnitude, and after which they gradually 

 decline and disappear, to make way for some newer and 

 advancing order. Or as it has been put by one of the most 

 recent writers on systematic geology (Professor Haughton), 

 "it appears to be an almost universal law of life on the 

 globe, that each group of organic beings increased in size 

 and in importance in an uninterrupted line from the com- 

 mencement of its existence, until its members reached their 

 maximum in some short time I mean, short as com- 

 pared with their whole life-history after their original 

 creation and appearance upon the globe ; and it would 

 almost seem as if, having reached that maximum of de- 

 velopment, they then commenced a process of degeneracy 

 and decline." 



Another remarkable feature in the tertiary fauna is the 

 prevalence of what are styled " intermediate forms," that 

 is, of creatures partaking of the characteristics of two or 

 more adjacent orders a sort of interfusion, as it were, of 

 families and genera, which now stand distinct and separate. 

 We have thus elephant-like tapirs, camel-like stags, giraffe- 

 like camels, horse-like antelopes, lion-like bears, tiger-like 

 hyaenas, and numerous other inosculating forms, which, 

 had they existed now, would have filled up more closely 

 the meshes of the great network of existence. Nor is it 



