UPPER AND LOWER 107 



the " Ludlow Rock," — one of the most modern deposits of 

 the Upper Silurian division \ [and subsequent discoveries, 

 both in England and America, had shown that even the hase 

 of this division has its ichthyic organisms. But for year 

 after year, the lower half of the system — a division more 

 than three thousand feet in thickness — had failed, though 

 there were hands and eyes busy among its deposits, to yield 

 any vertebrate remains. During the earlier half of the first 

 great period of organic existence, though the polyparia, ra- 

 diata, articulata, and mollusca existed, as their remains tes- 

 tified, by myriads, fish had, it was held, not yet entered upon 

 the scene ; and the assertors of the development theory 

 founded largely on the presumed fact of their absence. " It 

 is still customary," says the author of the " Yestiges of Crea- 

 tion," in his volume of " Explanations," " to speak of the 

 earliest fauna as one of an elevated kind. When rigidly 

 examined, it is not found to be so. In the first place, it 

 CONTAINS NO FISH. There were seas supporting crustacean 

 and molluscan life, but utterly devoid of a class of tenants 

 who seem able to live in every example of that element which 

 supports meaner creatures. This single fact, that only in- 

 vertebrated animals now lived, is surely in itself a strong 

 proof that, in the course of nature, time was necessary for the 

 creation of the superior creatures. And if so, it undoubted- 

 ly is a powerful evidence of such a theory of development as 

 that which I have presented. If not, let me hear an equally 

 plausible reason for the gi-eat and amazing fact, that seas were 

 for numberless ages destitute of fish. I fix my opponents 

 down to the consideration of this fact, so that no diversion 

 respecting high molluscs shall avail them." And how is this 

 bold challenge to be met X] 



It might be rationally enough argued in the case, that the 

 author of the "Vestiges" was building greatly more on a 

 piece of purely negative evidence, — the presumed absence of 



