102 DR. COCKS ON THE GROWTH, ETC., 
reappearance of many species of marine plants; 1 at length dis- 
covered that in this respect a very remarkable difference exists 
between these and land-plants. 
For instance:—dating from the period when I first became a 
collector, I ascertained that many of the plants which I originally 
found growing in certain localities did not invariably reappear 
under the same circumstances; that is to say, they either dis- 
appeared altogether, or remained in abeyance during the lapse of 
a series of seasons; whilst, in contrast, I found the same plants 
growing in quite a new and different locality. I observed also 
that there were а few species which I never found growing but in 
the very spots where they were originally discovered ; for instance, 
the “ Griffithsia secundiflora,” which was first found by my friend 
the Rev. Mr. Hore growing near Bovisand in 1846, where I have 
since been in the habit of taking it myself for many succeeding 
years, occurs, I believe, in no other place in Great Britain. 
I would also remark that, although I have visited this locality 
at all periods throughout the year, with the exception of three 
of the winter months, 1 have never yet found a single speci- 
men of this plant in fruit; but I am nevertheless inclined to 
believe that, if specimens could be taken in December, January, 
and February, they would be found to be in a state of fructifica- 
tion. The impediments are, however, very great. The place in 
which it grows is difficult of approach, even at the most favourable 
times, and then only in a boat. Whenever the wind blows from 
the south-west, or when the sea is rough, it is entirely unapproach- 
able; and besides, on reaching the spot, it is invariably found 
growing submerged to the depth of three or four feet at the lowest 
spring-tides. 
In the years 1844 and 1845, I was fortunate in collecting some 
very large and beautiful plants of Callithamnion roseum-—not ` 
an uncommon species. Since that period I have not succeeded 
in taking any so fine, and for the last three years I have not 
been able to secure a single good specimen. 1% is, however, 
rather remarkable that in the spring of last year (1858) a 
curious variety of this plant, which I had never before seen, made 
its appearance. It was found growing in singular abundance, 
and in several different localities ; and although I examined many 
hundreds of specimens, I did not succeed in finding a single one 
in а state of fructification. In the year 1849 I found another 
species belonging to the same genus, viz. a remarkably slender 
variety of Callithamnion pedicellatum, growing in luxuriant abun- 
