104 DR. COCKS ON THE GROWTH, ETC., 
approachable by a boat, а good many specimens of Chrysymenia 
rosea,—a plant which had never before been taken in Devon or 
Cornwall, a few only having been gathered by Mrs. Hayden and 
Mrs. Gattey in the year 1850 at Filey, on the Yorkshire coast. 
In the year following the one in which Dr. Budd and myself took 
our specimens, we found others growing in the same place; but 
afterwards they entirely disappeared from that habitat, though 
many other specimens have subsequently been found in several 
different localities, and, amongst others, growing on the mooring- 
buoys in the Sound. 
Again, in the years 1850 and 1851 a considerable number of 
specimens of that rather scarce plant, Microcladia glandulosa, were 
washed up with other rejectamenta upon the beach under the 
Plymouth citadel. These were all growing parasitically upon the 
fronds of Nitophyllum laceratum and Rhodymenia laciniata. Since 
that time no other specimens have been taken in this neighbour- 
hood, although the above-named plants on which they grew are 
still found as abundantly as ever. 
A still more singular occurrence remains to be noticed, viz. that 
of a single specimen being found of a species for which, from the 
first moment I became a collector until then, I had been dili- 
gently seeking, and which had also been carefully sought for, 
many years previously, by Mr. Hore, without success. I allude to 
Codium Bursa, a single plant of which I discovered growing on one 
of the mooring-buoys in Plymouth Harbour ; and although at the 
same time and subsequently I have examined all the buoys in the 
Sound as well as in the harbour, I have never found another. 
How then are the irregularities in reference to the time of 
appearance, as well as the disappearance of the plants I have before 
alluded to, to be explained? We know that the fructification of 
the marine Algew takes place with regularity; that is, the tetra- 
spores when arrived at maturity burst, and the spores are libe- 
rated, which are carried by currents to places where they attach 
themselves to some substance, and in due time vegetate and pro- 
duce perfect plants, similar to those from which they originated. 
Such being the case, although many of the plants enumerated 
in this paper have disappeared from their accustomed localities, 
yet it appears very strange, and difficult to explain why, they 
have not been found growing in other places, or washed on shore 
with other rejectamenta. 
These observations will, in part, tend to show, as I have before 
remarked, that the growth and periods of the appearance and re- 
