I 9 4 MODERN IDEAS OF EVOLUTION 



back, in the rocks of the Levis division of the Siluro- 

 Cambrian system in Canada, I have found in a single 

 thin bed of shale, representing a muddy sea-bottom 

 of that age, a dozen species of several genera, all 

 bearing testimony to the perfection of this plan of 

 structure at that early date. Salter and Matthew 

 have found in still older Cambrian rocks species of 

 these sponges having delicate spicules still retaining 

 their arrangement, and showing that this beautiful 

 contrivance for the support of a gelatinous animal 

 existed in all its perfection almost at the dawn of 

 life. Through all these vast periods of geological 

 time the hexactinellids have continued side by side 

 with the lithistid sponges, their allies ; and contem 

 poraneously with them the rhizopods and radio- 

 larians, still more simple forms, have built up other 

 styles of skeletons equally wonderful and inexplicable, 

 and embodying other mechanical plans and other 

 types of beauty. 



It is scarcely too much to say that no sane mind 

 having presented to it, not as above merely in a few 

 words, but in the actual facts as they might be illus 

 trated with specimens and figures, all this unity and 

 variety, mechanical contrivance and varied beauty, 

 associated with so little of vitality and complexity in 

 the animals concerned, could doubt for a moment 

 the action of a creative intelligence in the initiation 

 of such phenomena, or could believe that they have 

 resulted from the fortuitous interaction of atoms. 



