526 SUCCESSION OF LIFE IN TIME. 



appears to have been a walker rather than a climber, and intermediate 

 between Semnopithecus and the Macaques. The anthropomorphous 

 apes include PliopitTiecus and Drt/opithecus. The latter is of a very 

 high type, but differs from man in many points, but especially in the 

 large size of the canines in the males. 



Professor Gaudry considers that the doctrine of evolution would 

 justify us in regarding a European deposit as Eocene if the mammals 

 were numerous but unlike those now living, and unassociated with true 

 ruminants, solipeds, proboscidians, and apes. In the older Miocene 

 we should expect to find living genera rare, marsupials disappearing, 

 pachyderms passing into horses, and the incoming of true ruminants. 

 In the newer Miocene marsupials would be lost ; but ruminants, 

 horses, whales, edentates, elephants, carnivora, and apes are represented 

 by numerous individuals and many genera, some of which diverge 

 from living forms. In the Pliocene period the genera are mostly still 

 living, though the species are extinct. 



Summary. If we endeavour to summarise the conclusions which 

 the succession of life on the earth indicates, the most important 

 generalisation is no doubt the fact that the life now existing is sub- 

 stantially the same as life has been in all the past ages of time. The 

 combination of the different groups of organisms is of like character, 

 though the genera and species have varied. There is no trace of 

 a beginning. There is evolution, but it is only the evolution of 

 genera and of ordinal groups, and not of classes. 



It is chiefly by means .of extinct families and orders that strata are 

 characterised, and the periods of past time separated from each other ; 

 but when we bear in mind what the circumstances are which are 

 causing extinction at the present day, we may doubt whether a classi- 

 fication so made is the best possible. Its method is unphilosophical. 

 At least of equal importance with the occurrence of extinct types is 

 the first appearance as elements in a fauna of genera and orders which 

 still survive ; for both are connected with the changed distribution 

 of land and water which time has developed. The first appear- 

 ance of organisms as a characteristic feature in a fauna, would divide 

 the strata differently from the extinct types, and would show how 

 local are all the phenomena of the succession of life. Many groups 

 of organisms which still survive appear plentifully in the Cretaceous 

 rocks, so that a palseontological division might be drawn on the 

 evidence of plants and fishes and many intermediate groups of organ- 

 isms, which link the Lower Greensand with strata below, and the Gault 

 with strata above. The Trias is sharply cut off from the Lias above, 

 and from Permian rocks below. The Primary period is certainly 

 divided into two by a gap in succession of species between the upper- 

 most beds of the Silurian and the lower part of the Devonian, which 

 is not less marked than the other great changes in life, such as divide 

 the Secondary and Tertiary rocks, or the Trias and Lias. 



The names Palaeozoic, Mesozoic, and Cainozoic, therefore, do not 

 represent completely palaeontological facts, and the divisions which 

 they indicate are artificial when studied in the light of the groups of 



