INTRODUCTION. 
cuspidate and diaphanous in some states of J. barbata (tab. 70): but none of the genus 
have ever, that I am aware of, a liair-like termination, which is so common among the 
leaves of the Mosses. 
There are many species whose leaves are cleft into two segments of (generally) Division, 
unequal sizes ; and these segments are conduplicate, or more or less folded and appressed 
to each other. I say generally, because, in J resupinata (tab. 23), we have an example of 
nearly, and sometimes quite, equal conduplicate segments. In the rest they differ in size, 
and somewhat in figure. The division is slight in J. exsecta (tab. 19) and J. miriuta 
(tab. 44) : in some others, such as J. complunata (tab. 81), J. Mackaii (tab. 53), J. hamati- 
folia (tab. 51), and J. minutissima (tab. 52), the leaf might rather be described as having 
a small lateral appendage, which is usually involute, than as being divided into two 
segments ; but a regular gradation from J. minutissima , through J. serpyllifolia, J. Mackaii, 
and J . complanata, to those which are strikingly two-lobed, is so imperceptible, that it is 
not possible to draw a line of distinction. 
In other species the lobes are deeply divided, particularly in J. umbrosa (tab. 24), 
J. platyphylla (tab. 40), J. undulata (tab. 22), J. nemorosa (tab. 21), and J. planifolia 
(tab. 67). In this last species, many of the leaves are divided down to the very stem; in so 
much that I have been led to describe the two lobes as distinct leaves, which, in fact, they 
are, in some parts of the plant, whilst, in others, subsequent examinations have enabled me 
to discover these lobes united, and resembling so nearly those of J. nemorosa (tab. 21), 
that I should be tempted to regard it as a variety of that plant, did not my friend. 
Dr. Taylor, who has gathered it on its native mountains, hold quite a different opinion. 
In every instance, the larger segment or lobe is plane, or more or less concave; 
remarkably so in J. minutissima (tab. 52) : in J. calyptnfolia (tab. 43), calyptriform. The 
smaller one is more variable, being plane in J. platyphylla (tab. 40), J. nemorosa, &c. : 
involute in J. Mackaii, J. complanata, J. serpyllifolia, and J. calyptrifolia : saccate in 
J. cochleariformis (tab. 68), J. Hutchinsia (tab. 1), J ■ dilatata (tab. 5), and J. Tamarisci 
(tab. 6). 
The larger lohe is sometimes again divided, as in J. Woodsii (tab. 66) and J. ciliaris 
(tab. 65) : in J. cochleariformis it is notched at the apex. The smaller one is, I believe, in 
every instance entire. 
In all the kind of leaves the margins are for the most part entire : serrated in Margin*. 
J. albicans (tab. 15) and J. umbrosa (tab. 24) : dentate in J. asplenioides (tab. 13): spinoso- 
dentate in J. spinulosa (tab. 14), J. Hutchinsia, and J. Woodsii: beautifully ciliated in 
J. ciliaris (tab. 65) : and finely laciniate in J. tomentella (tab. 36). 
If the structure of the stems be simple, so likewise is that of the leaves ; for it is the Structure, 
same in both: a tissue of cellules, of a roundish or ovate figure, sometimes, from the 
closeness with which they are placed, appearing hexagonal. I cannot satisfy myself that 
there really exist any pores in these cellules, though I have thought I saw traces of them 
in those of J. juniperina. They are filled with a pellucid liquor, and colored granules, 
green in the greater number of species ; brown in J. juniperina ; and purple in some of the 
varieties of J . nemorosa, J . cochleariformis, and J. compressa. 
