120 



FISHES OF THE SILURIAN ROCKS» 



tion, the naturalist catches a glimpse in fording the unknown 

 lake, it at least serves to show that all the Silurian ichthyolites 

 must not be described as small, seeing that not only might many 

 of its undetected fiijh have been large, but that some of those 



Fig. 53. 



a. Posterior Spine of Spinax A canthias. h. Fragmen t of Onondago Spine. 

 (Natural Size.) 



which have been detected were actually so. Another Ameri- 

 can spine, of nearly the same formation, — for it occurs in a 

 limestone, varying from twenty to seventy feet in thickness, 

 which immediately overlies that of the Onondago deposit, 

 though still more fragmentary than the first, for its length 

 is only two three-eighth inches, — maintains throughout a 

 nearly equal thickness, — a circumstance in itself indicative 

 of considerable size ; and in positive bulk it almost rivals the 

 Onondago one. Of the Lower Silurian and Bala fishes no 

 descriptions or figures have yet appeared. And such, up to 

 the present time, is the testimony derived from this depart- 

 ment of Geology, so far as I have been able to determine it, 

 regarding the size of the ancient Silurian vertebrata. " No 

 organism," says Professor Oken, " is, nor ever has one been 

 created, which is not microscopic." The Professor's pupils 

 and abettors, the assertors of the development hypothesis, 

 appeal to the geological evidence as altogether on their side 

 in the v'>»«''e ; and straightway a few witnesses enter court. But. 



