growth. These characters, taken im addition to the robust 
threads, spreadmg branches, and blunt ramuli may serve to 
distinguish it from our other marine kinds, but it is more diffi- 
cult to point out characters by which it may be known from a 
fresh-water species, C. glomerata. Almost all authors, indeed, 
who have written on the genus seem disposed to regard C. lete- 
virens as a marine variety of C. glomerata, attributing what 
minor differences may be seen to a difference of locality. This 
is the view taken by Agardh, and adopted in Hooker’s British 
Flora. Mrs, Griffiths, however, who has paid much attention to 
plants of this genus, and to whose acute eye we owe the detection 
of more than one new form among them, is of a different 
opinion, and, at her instance, I have in another place restored 
C. letevirens to the catalogue: whilst I express my doubts of the 
propriety of such a step. Among such imperfect plants Aadztat 
may, perhaps, be admitted as a character of no ordinary im- 
portance, and if we allow it in the present case, there can be no 
difficulty in the matter ; for C. /etevirens is found in the open 
sea, beyond all influence of fresh water, and C. g/omerata in rills 
and rivers remote from the sea, and often hgh among the hills. 
Practically, therefore, and as far as collectors are concerned, the - 
plants may be allowed to be distinct. But when we come to 
speak of the physical distribution of species, it should be borne 
in mind that these marine and fresh-water plants are, perhaps, 
different states of the same thing. A similar instance of an Alga 
srowing in the open sea and in fresh water, occurs in Bangia 
fusco purpurea, which is often found in fresh-water streams in 
very inland situations; but instances of such indifference in 
habitat are very unusual. 
Fie. 1. CLADOPHORA LEHTEVIRENS :—of the natural size. 2. Part of a branch. 
3. Ramuli:—more or less highly magnified. 
o 
o- 
