COSMIC PHILOSOPHY 



which seemed before very widely separated : far 

 closer will such links be drawn when a consid- 

 erable portion of the earth's surface shall have 

 been thoroughly investigated. 



The argument from " missing links/' there- 

 fore, in so far as it has any validity at all, is an 

 argument which rests entirely upon negative 

 evidence. But negative evidence, as every one 

 knows, is a very unsafe basis for argument.^ A 

 single item of positive evidence will always out- 

 weigh any amount of negative evidence. A 

 single case in which two or three species of 

 genera are demonstrably connected with each 

 other through lineally intermediate forms, is 

 enough to outweigh the case of a thousand 

 species or genera in which no such linear con- 

 nection has yet been demonstrated. Now there 

 can be no question that Equus^ Hipparion^ and 

 Anchitherium are quite distinct genera ; and a 

 comparison of the skeletons of the three leaves 

 it equally unquestionable that the hipparion is 

 simply a more ancient horse, and that the anchi- 



1 ** For instance, the several species of the chthamalinze (a 

 sub-family of sessile cirrhipeds) coat the rocks all over the 

 world in infinite numbers : they are all strictly littoral, wdth 

 the exception of a single Mediterranean species, which inhab- 

 its deep water, and this has been found fossil in Sicily, whereas 

 not one other species has hitherto been found in any tertiary 

 formation : yet it is known that the genus chthamalus existed 

 during the Chalk period. ' * Darwin, Origin of Species, 6th edi- 

 tion, p. 271. 



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