Fossil Cryptogams^*

Abstract

I DO not propose at present to controvert in detail all the positions taken up by my friend Prof. McNab in his brief communication to your pages on “Fossil Cryptogams” (vol. vii, p. 267), because the time has not yet arrived for doing so. Much more detailed information respecting the subject which yet awaits publication must be had before it can be discussed in a satisfactory manner. I merely wish to avoid leaving the impression, by my silence, that I either admit his supposed facts or accept his inferences. When his paper, to which he refers, was read in Edinburgh, specimens of sections of Calamites of various ages were sent down by me for the purpose of being exhibited to the Botanical Society. This was done by Prof. Dickson, who at the same time expressed his preference for my views over those of Dr. McNab, as is stated in the officially published notice of the meeting in question. Since then I have received a kind letter from Dr. Balfour, who has carefully examined the specimens referred to, and who also expresses a similar conviction. I think that I have unmistakeable proof of the circumferential growth of Calamites, which Dr. Macnab denies, in specimens of large size, and in which the exogenous zone is of great thickness.