326 LIFE AT DOWN. ^TAT. 33-45- [1847. 



Thirdly, it never entered my head to undervalue botanical 

 relatively to zoological evidence ; except in so far as I thought 

 it was admitted that the vegetative structure seldom yielded 

 any evidence of affinity nearer than that of families, and not 

 always so much. And is it not in plants, as certainly it is in 

 animals, dangerous to judge of habits without very near 

 affinity. Could a Botanist tell from structure alone that the 

 Mangrove family, almost or quite alone in Dicotyledons, 

 could live in the sea, and the Zostera family almost alone 

 among the Monocotyledons ? Is it a safe argument, that be- 

 cause algae are almost the only, or the only submerged sea- 

 plants, that formerly other groups had not members with 

 such habits? With animals such an argument would not be 

 conclusive, as I could illustrate by many examples ; but I am 

 forgetting myself ; I want only to some degree to defend my- 

 self, and not burn my fingers by attacking you. The founda- 

 tion of my letter, and what is my deliberate opinion, though I 

 dare say you will think it absurd, is that I would rather trust, 

 c ceteris pa7'ibus^ pure geological evidence than either zoological 

 or botanical evidence. I do not say that I would sooner trust 

 poor geological evidence than good organic. I think the basis 

 of pure geological reasoning is simpler (consisting chiefly of 

 the action of water on the crust of the earth, and its up and 

 down movements) than a basis drawn from the difficult sub- 

 ject of affinities and of structure in relation to habits. I can 

 hardly analyze the facts on which I have come to this con- 

 clusion ; but I can illustrate it. Pallas's account would lead 

 any one to suppose that the Siberian strata, with the frozen 

 carcasses, had been quickly deposited, and hence that the 

 embedded animals had lived in the neighbourhood ; but our 

 zoological knowledge of thirty years ago led every one falsely 

 to reject this conclusion. 



Tell me that an upright fern in situ occurs with Sigillaria 

 and Stigmaria, or that the affinities of Calamites and Lepido- 

 dendron (supposing that they are found ijt situ with Sigillaria) 

 are so clear^ that they could not have been marine, like, but 

 in a greater degree, than the mangrove and sea-wrack, and I 



