438 



Such an idea does not enter into my philosophy as a possibility let 

 alone a probability. 



What I actually said was as follows »from its archaic character 

 Nautilus might be expected to give valuable hints as to the phylo- 

 genetic relationships of the group to which it belongs. Upon the 

 whole it appears to me that its structure affords strong evidence that 

 the nearest living allies of the Cephalopoda are to be found in 

 the Amphineura. And amongst these it is interesting to note that it 

 is the Chitons in which the points of resemblance are most striking 

 as they are apparently the oldest and most primitive members of the 

 group« (P.Z.S. 1S95. p. 683). 



And again: 



y) Nautilus shows many strong resemblances to the Amphineura 

 and it is probably amongst these latter that we have to look for the 

 nearest allies of the Cephalopoda« (op. cit. p. 686). 



It will, 1 think, be quite clear from these quotations that the 

 view expressed in 1895 was merely that the Chephalopoda are more 

 nearly allied to the Amphineura than they are to any other subdivision 

 of the mollusca, in other words, that the ancestral group common to 

 the two groups was probably more recent than that common to either 

 of them and any other group of molluscs. This, as will be seen, is 

 very different from believing that one group is actually derived from 

 the other, and in fact it goes but little further than does Prof. Plate 

 himself, who allows that the Chitons and the Cephalopods »auf die- 

 selbe Wurzel sich zurückführen lassen«. 



My object is now merely to correct an erroneous impression 

 conveyed by Prof. Plate's criticism and I do not venture to criticise 

 his real arguments, which coming from him must naturally be given 

 the greatest weight. In regard to one point, however, I should like 

 to make a few remarks. 



Prof. Plate criticises in turn each of the points of resemblance 

 brought forward by me between Nautilus and Chiton and shows how 

 each in turn is quite inadequate to justify the assumption of close 

 genetic connection between the two forms. In regard to this I agree 

 absolutely with Prof. Plate that each of these resemblances taken 

 by itself is of no special account: I might go further and say that 

 I believe no isolated resemblances however striking can be of value 

 upon which to rest theories of affinity : when on the other hand there 

 occur, say half a dozen points of resemblance, in deep seated morpho- 

 logical features without any apparent adaptive relations to conditions 

 of existence, between two types then I believe that taken all 

 together they do constitute important evidence of genetic relationship. 



Cambridge, May 12. 



