TRILOBITE HUNTING. 209 



to substantiate that theory have certainly proved 

 fruitful in bringing to light many homologies of 

 structure in the vegetable and animal world that 

 had previously been overlooked. There are, it is 

 true, many respected students of Nature who fail 

 to see in homologous structures an invincible argu- 

 ment in favour of community of origin, and who 

 therefore regard evolution as unproved, but who 

 nevertheless accept it provisionally or as a valuable 

 working hypothesis. 



In any inquiry bearing on the origin of au animal 

 form, Geology of course must be heard. But in 

 regard to the ancestry of the trilobite Geology is 

 singularly deficient in supplying suggestions. When 

 trilobites had already reached their zenith there 

 were but a few phyllopod crustaceans in existence, 

 and these were far removed from the trilobite in 

 structure, while no contemporaneous mollusc throws 

 the least light on the subject. Darwin says (Origin 

 of Species, p. 286) : " It cannot be doubted that'all 

 the Cambrian and Silurian trilobites are descended 

 from some one crustacean which must have lived 

 long before the Cambrian age." If the evolution 

 theory be true, this of course is so ; but it ought to 

 be pointed out that an ipse dixit of this sort is 

 entirely destitute of argumentative value. It is an 

 admission that palaeontological records fail to reveal 

 the ancestry of the trilobite. Barrande, than whom 

 no one can speak with greater authority on trilobites, 

 went so far as to say that their evolution was " un 

 produit de Fimagination, sans aucun fondement 

 dans la realite." 



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