III.] INDEPENDENT SIMILARITIES OF STRUCTURE. 87 



so far from it, in his lecture on this subject at the Royal 

 Institution before referred to, he observes : * " I can testify, 

 from personal experience, it is possible to have a complete 

 faith in the general doctrine of evolution, and yet to hesi- 

 tate in accepting the Nebular, or the Uniformitarian, or 

 the Darwinian hypotheses in all their integrity and ful- 

 ness." f 



It is quite consistent, then, in the professor to explain 

 the difficulty as he does ; but it would not be similarly so 

 with an absolute and pure Darwinian. 



Yet stronger arguments of an analogous kind are, how- 

 ever, to be derived from the highest organs of sense. In 

 the most perfectly-organized animals those, namely, which, 

 like ourselves, possess a spinal column the internal organs 

 of hearing consist of two more or less complex membranous 

 sacs (containing calcareous, particles otoliths), which are 

 primitively or permanently lodged in two chambers, one on 

 each side of the cartilaginous skull. The primitive cartila- 

 ginous cranium supports and protects the base of the brain, 

 and the auditory nerves pass from the brain into the cartila- 

 ginous chambers to reach the auditory sacs. These com- 

 plex arrangements of parts could not have been evolved by 

 "Natural Selection," i. e., by. minute accidental variations, 

 except by the action of such through a vast period of time ; 

 nevertheless, it was fully evolved at the time of the deposi- 

 tion of the upper Silurian rocks. 



Cuttle-fishes ( Cephalopoda) are animals belonging to the 

 molluscous primary division of the animal kingdom, which 

 division contains animals formed upon a type of structure 

 utterly remote from that on which the animals of the 

 higher division provided with a spinal column are construct- 

 ed. And indeed no transitional form (tending even to 

 bridge over the chasm between these two groups) has ever 



9 " Proceedings of the Royal Institution," roL v., p. 279. 



