568 MANUAL OF ZOOLOGY. 



Species of this genus must have been as large as a Lion. In 

 the later Pliocene and Post-pliocene deposits occur the remains 

 of a large Lion the Cave-lion or Fdis spelcea along with 

 which, in Britain and continental Europe, are the bones of a 

 large Hyaena (H. spelaa) and a gigantic Bear ( Ursus spelaus). 

 Remains of Wolves, Foxes, Badgers, Otters, Pole-cats, Weasels, 

 and other Carnivora are also found in various later Tertiary 

 deposits, and in bone-caves. 



Order X. Rodentia. No Rodent animal is as yet known to 

 have occurred earlier than the Eocene period. Here are found 

 forms allied to the living Dormouse and Squirrel. In the 

 Miocene Rocks occur numerous small Rodents. In the Plio- 

 cene and Post-pliocene deposits the order is also well repre- 

 sented, the most remarkable form being the great Beaver 

 (Trogontherium), which appears to have survived into the his- 

 torical period. 



Order XL Cheiroptera. The earliest-known indications of 

 Bats are in the Eocene period, but the order is of no geological 

 importance. 



Order XII. Insectivora. The Insectivorous Mammals, r like- 

 wise, commenced their existence, so far as is known, in the 

 Eocene period ; and they, also, are of no importance from a 

 geological point of view. 



Order XIII. Quadrumana. The earliest-known remains of 

 Quadrumana occur in the Miocene period. Several genera 

 are known, but the most important are Pliopithecus and Dryo- 

 pithecus, both of which are European, and both of which belong 

 to the section of the Catarhine Monkeys which are at present 

 characteristic of the Old World. They appear to be most 

 nearly allied to the recent Gibbons. It is interesting to notice 

 that the American fossil Monkeys from the later Tertiary 

 deposits of South America belong to the division of the Quad- 

 rumana now peculiar to that continent to the section, 

 namely, of the Platyrhine Monkeys. 



GEOGRAPHICAL SUCCESSION OF ORGANIC FORMS. 



A few words may be said here on a law which may be called 

 the " law of the geographical succession of organic forms," and 

 which is illustrated more completely by the Mammalia than by 

 any other extinct animals. An examination, namely, of the 

 facts of the geological distribution of Mammals leads to the 

 striking generalisation that " the present distribution of organic 

 forms dates back to a period anterior to the origin of existing 

 species" (Lyell). In other words, though the extinct Mam- 



