Frof. Gauclry on Tertiary Mammalia. 467 



The above list shows the great development of Herbivora, a charac- 

 teristic feature of the close of the Miocene period. Daring the 

 Calcaire Grossier and Gypsum period of the Paris Basin, the 

 pachyderms predominated ; the Zophiodon, Choeropotamus, Myra- 

 cotherium, Paloeoilierium, AncMlophus, and AnoplotJiermm. The most 

 herbivorous animals were the Xipliodon, Dichodon, and Amjohimeryx, so 

 near the pachyderms that some Naturalists range them in the same 

 order. Although found in the Lower and Middle Miocene with 

 some modifications in their dental structure, and the more or less 

 anchylosed character of the metatarsal bones, as in the Gelocus, 

 Drematherium, and Andiitliermm, it was in the Upper Miocene that 

 the Herbivora were most largely developed. The Giraffe and Hella- 

 dotlierium attained a size unknown among preceding ruminants, the 

 Antelopes and Stags were of more varied forms, the Hipparion sue- . 

 ceeded the AncMtlierixim. M. Gaudry does not consider the prairies 

 resembled those of northern Europe at present, for, from the cha- 

 racter of the dentition of the animals, the grasses did not form an 

 important part of the vegetation with which the countiy was then 

 covered. During the Pliocene, Quaternary, and present (or Modern) 

 periods the ruminants, as well as the Solipedes (or Eqiddcd), were 

 very numerous in Europe, and the prairies were more extended. 

 The evolution of the Carnivora followed that of the Herbivora. At 

 the commencement of the Eocene period the beasts of prey were of 

 small size and not numerous ; the Hycenodon and Pterodon did not 

 exceed the size of the wolf. Soon after appeared the great Amphicyon, 

 in character intermediate between the bear and the dog;, inclining 

 one to the belief that they were probably omnivorous in habit, and 

 devoured more dead flesh than living prey. It was at the close of 

 the Miocene period that the Carnivora arrived at their apogee, and 

 were represented by two extreme types, the Jlycena and the 

 Macliairodus. 



H. — Palaeontologists have often supposed that a great difference 

 existed in the variation of the higher as contrasted with the lower 

 types- of organic beings. Indeed it has been considered that many 

 of the Miocene Mollusca, as well as a certain number of the Eocene, 

 were identical with living species ; on the contrary, the Mammalia 

 appear to have been restricted to certain geological horizons ; thus 

 the LopModon is found only in the Middle Eocene, the Pahcotherium 

 only in the Upper Eocene, the Bhinoceros does not appear below the 

 Miocene; so that we are fully entitled to say "the age of LopModon" 

 "the age of Palceotherium,'' and " the age of RJiinoceros.'" 



But on the other hand a minute examination of the older species 

 of the Tertiary Mollusca has shown characters which distinguish 

 them in general from living species. 



MM. Deshayes, Fischer, and other conchologists, who have studied 

 the relations of the Tertiary species, think that the absolute identity 

 is not very common among the Mollusca of different ages ; on the 

 other hand, the researches of MM, Tournouer, Thomas, etc., have 

 shown that the Palceotherium has been contemporary with the 



