NOTICES OF BOOKS. 157 
share of our attention in former years,—the Classes or Orders (for these 
terms are used in the same or in different senses) do not seem as yet to 
be capable of being divided into tangible groups or suborders with the 
same facility as in the case of corresponding groups in Phænogamous 
plants: they appear so insensibly to pass one into another, that they 
can neither be defined by the pen or pencil, or even neatly distinguished 
by the eye. We have felt and expressed this repeatedly in our at- 
tempts to group the Ferns according to their natural affinities: and 
we feel sure that were Mr. Wilson and Dr. Schimper each to be en- 
gaged independently of the other, in working out a natural arrangement 
of the Mosses, they would come to very different conclusions in respect 
to the extent or limits of the suborders :—so insensible are the passages 
between any given group and its neighbouring, or indeed some distant, 
groups. The arrangement 7s nevertheless, we would rather say, on that 
account, a natural one; as far as a linear arrangement can be so. But 
here follows the difficulty :—they are incapable of definition: and so 
sensible does Mr. Wilson appear to be of this, that with that honesty of — 
purpose which is so remarkably his character, he declines to offer any 
definition. With the exception of Audreeacee and the Sphagnacee —— 
(which might ds well be excluded from Musci as a natural group, as —— 
are the Hepatice), each consisting of a single genus, and as such cha- — 
racterized, ald the rest of the Mosses are included in the third Order, 
Bryacee ; but neither is that, nor any of the thirty-six suborders in- 
cluded under it, distinguished by a word of character or explanation. . 
We think however, at p. 53, under the fourth suborder, Se/igeriee, we 
find an apology, and what is intended in some sort as a remedy, in the — 
following statement:—* To avoid prolixity, we shall refer our readers 
to the descriptions of the genera for an idea of the respective suborders 
to which they are supposed to belong. There is much to be learned 
before the exact limits of each group can be ascertained ; meanwhile it is 
our purpose to proceed on the plan laid down in the * Bryologia Europea’ 
in all cases where good reasons to the contrary do not appear.” eno 
If indeed there was no other arrangement in the volume but that 
just alluded to—the Natural—with the absence of characters for the 
subdivisions, a person not an adept in the science, who might take P 
and seek to determine a given genus,—Fontinalis, for example, which 
is placed near the close of the arrangement,—would have to wade 
through the descriptions of all the first eighty-eight genera of Argant, 
* 
