1899] EARLY LIFE ON EARTH 185 



There is not much professedly original in the address ; but when 

 most people are trying to overcome difficulties by postulating a more 

 rapid rate of variation in the early stages of organic life on earth, it is 

 interesting to find Captain Hutton believing in a slower rate of variation 

 at that period. He bases this Antipodean view on the great thickness 

 of Archaean and early Palaeozoic rocks, and considers that the repre- 

 sentation of all the sub-kingdoms of animals in fossils of Cambrian, or 

 at all events of Ordovician age does not imply so great an amount of 

 evolution as do the subsequent developments. " It was this slow rate 

 of variation in ancient times that enabled the early Palaeozoic genera 

 to spread so much more widely over the earth than do the genera of 

 the present day." It must not, however, be forgotten that some would 

 ascribe the great relative thickness of early sediments to greater 

 intensity of denudation on an earth unprotected by vegetation. 



The Passing of the Vanquished. 



The extinction of whole groups of animals, as of the graptolites in the 

 Carboniferous period, and the trilobites in the Permian, has always 

 been a puzzle to naturalists, and on this Captain Hutton has some 

 suggestive remarks. The existence in early times of Eadiolaria, almost 

 identical in structure with their descendants of the present day, 

 suggests to him, in opposition to the views of H. S. Williams, " that 

 there is no inherent necessity for organisms to vary or decay, while the 

 idea that if they vary then they must subsequently decay is opposed to 

 the whole teaching of organic evolution, for it is the variable groups 

 which have progressed." The extinction of a whole group must there- 

 fore be due to external agencies, and if the group was widely spread, 

 these cannot have been local in their operation. 



Change of climate may, perhaps, sometimes account for the exter- 

 mination of a group of terrestrial animals or plants, but it cannot 

 greatly have affected those living in the sea. " The struggle for exist- 

 ence with other animals has, no doubt, generally been the most effi- 

 cient cause of extinction, and with pelagic animals it is probably the only 

 cause." The graptolites can hardly have succumbed to want of food, 

 but probably served as food for others. Those others may have been 

 medusae or pelagic cephalopods. Captain Hutton favours the latter, 

 but admits that we know very little about them. The trilobites, on 

 the other hand, were, he thinks, preyed upon by the ground cephalopods, 

 which increased in numbers as the trilobites decreased. In vain the 

 latter acquired the power of rolling up into a ball : " the ruthless 

 intruders turned them over and tore out their insides." 



We have unrolled Captain Hutton's pamphlet, turned it over and 

 torn out its inside for our readers. But we hope that the gallant 

 author will not become extinct just yet. 



