226 
that he entertained them; and they were incidentally mentioned in 
print both by Dr. Seemann and myself. Mr. Smith’s matured views 
on the subject were first published in the sixth Part of Dr. Seemann’s 
* Botany of the Voyage of H.M.S. Herald,’ at p. 226, in the following 
words:— 
“In this enumeration I have followed the arrangement published 
by me in Hooker's ‘Journal of Botany,’ vol. iv. p. 46 et seq., except in 
such cases where later observations and altered views have rendered 
ehanges necessary. In my enumeration of the ferns cultivated in the 
Royal Botanic Gardens at Kew (‘ Botanical Magazine,’ vol. Ixii. 1846) 
I arranged the species of Polypodium under four sections, charac- 
terized by the different modes in which the fronds are developed and 
attached to the axis of growth (vernation). The first of these sections 
contains Polypodium vulgare, which, with its allies, presents a mode 
of growth quite different from that of those species constituting the other 
three sections; the three latter I now consider as presenting only dif- 
ferent modifications of another and more general mode of growth; 
and although all the species of the four sections agree in the techni- 
cal character of Polypodium, in having punctiform naked sori seated 
on free veins, yet the two different modes of growth found in the 
various species of Polypodium appear to me to be quite sufficient to 
warrant a separation of the species under distinct genera. I there- 
fore restrict true Polypodium to those species having the same kind 
of vernation as Polypodium vulgare. The genus may then be 
viewed as representing a natural group of ferns having the following 
characters :—The fronds are developed from the sides of a special 
thizome, which has its axis of growth always in advance of the nas- 
cent frond (excurrent); the fronds are produced from nodes more or 
less distant from each other, each node producing a single frond, 
which, after having arrived at maturity, separates by a special articu- 
lation formed between the node and the base of the stipes; after the 
frond has fallen, the node remains in the form of a round, concave 
cicatrix, generally more or less elevated; the rhizome is solid, fleshy 
and brittle, varying from long and slender to more or less short and 
thick, and is always covered with scales, which, unless they are com- 
mon to the whole frond, seldom extend upwards beyond the node. 
This mode of development, which I have termed Eremobrya, is pe- 
culiar to a considerable number of Polypodiew, including genera with 
both free and anastomosing veins; also a portion of Davallia, of 
which D. Canariensis may be viewed as the type, the whole forming 
a truly natural group of ferns. The other mode of development 
