May 1, 1897.] 



KNOWLEDGE. 



113 



our own times was only an advanced and special study on 

 Smith's principles. Lyell established the well-known 

 terms, Pliocene, Miocene, and Eocene, and showed what 

 immense changes had gone on in the earth's surface even 

 during these more recent periods. His demands on time 

 were naturally repugnant to those who still held that the 

 earth and all that therein is had existed for only some six 

 thousand years ; and physicists, even in later times, have 

 stoutly opposed the geologists in their views of the extreme 

 antiquity of life 

 upon the globe. 

 In the last few 

 years, however 

 — as Mr. Poul- 

 ton has very 

 clearly set forth 

 in his address to 

 the zoological 

 section of the 

 British Associa- 

 tion in 1896— 

 physical experi- 

 ment has shown 

 that the earth's 

 crust would 

 have reached 

 its present tem- 

 perature, on the 

 surface of a 

 cooling globe, 

 in a time vastly 

 longer than the 

 physicists were 

 formerly able to 

 concede ; and, 

 consequently, 

 geological time, 

 though of 

 course not 

 limitless, may 

 be restored to 

 us in something 

 like the propor- 

 tions insisted 

 on by Lyell. 



It is thus 

 much more easy 

 to conceive the 

 successive evo- 

 lution of the 

 various life- 

 zones that 

 mark out the 

 strata one from 

 another. In 

 1859, Charles 

 Darwin's " Ori- 

 gin of Species " 



afforded satisfactory reasons for regarding fossil organisms 

 as a continuous series, the forms of one geological 

 epoch having descended from those of a previous one ; 

 and fossils, instead of being treated as more or less 

 imperfect experiments in creation, became the essential 

 alphabet whereby we may trace out the progress of life 

 upon our planet. It was only to be expected that at first 

 many rash genealogies should be put forward, and that 

 many supposed " connecting links" should have later to 

 be shorn away. Even at the present time, the methods of 

 William Smith, involving patient observation as to the 



Sib Charles Ltezl 



relations of the beds themselves, form the only safe basis 

 in deciding the succession of life-forms. 



The PalfEontographical Society undertook in 1847 the 

 description and delineation of all British fossil species ; 

 and the magnificent series of quarto volumes issued up to 

 the present time more than rivals the ambitious publica- 

 tions of the opening years of the century. Owen, who 

 seemed a lineal successor of Cuvier, brought together into 

 the collections of the British Museum a series of fossil 



vertebrates 

 from all lands ; 

 and many of 

 Huxley's laurels 

 were gathered 

 while investiga- 

 ting similar 

 remains. The 

 discovery of the 

 relationships 

 in structure 

 between the 

 skeletons of 

 many of the 

 cumbrous rep- 

 tiles of the 

 Mesozoic era 

 and the light- 

 limbed birds 

 that seem to 

 have arisen side 

 by side with 

 them, is one 

 of the most 

 striking results 

 of these studies 

 in comparative 

 anatomy. WhUe 

 Mantell, Owen, 

 Hulke, Seeley, 

 and other work- 

 ers have put 

 before us the 

 variety and rich- 

 ness of British 

 reptilian re- 

 mains. Marsh 

 and Cope have 

 attacked the 

 American fossil 

 vertebrates, and 

 have restored 

 a long series 

 of Dinosaurs, 

 from the Trias 

 to the highest 

 beds of the 

 Cretaceous, 

 which have 

 given us altogether new conceptions of the age of giant 

 reptiles. At the same time, the Permian and Triassic 

 reptiles of Texas and South Africa have been shown to 

 embody hints of the incoming of the mammals, the group 

 of the "Theromorpha '' being far less specialized along the 

 reptilian line than are the reptiles of the present day. 

 Owens Tritiiloilon, from the Karoo beds of South Africa, 

 remains our best-preserved and oldest mammalian skuU ; 

 and the recent investigation of the milk-teeth of Ornitho- 

 rhynchm has shown relationships between the earliest known 

 mammals and the lowest existing order, the monotremes. 



