ON THE GENERA ANADYOMENE AND MICRODICTYON. 71 
genus, or a species, that has neither occurred to me in any work no 
herbarium. : 
ADDITIONAL NOTES ON ANADYOMENE. 
Since the printing of the first portion of this paper, Dr. Harvey has 
kindly sent me some notes on it, and some additional specimens for 
my collation and for examination. - 
His specimen of Grayemma Menziesii is much smaller than the one 
in the British Museum, and a considerable number of the filaments 
are formed of a single series of cells, but all these simple lines of single 
cells are continued for the length of several cells, without giving out 
any branches ; they terminate in three or four equal cells, which are 
continued side by side according to what I consider the normal struc- 
ture of the plant, or, after one or two such groups of cells, they split 
off again into long threads, formed of a single series of long linear cells, 
one on the end of the other. These varieties confirm me in the dis- 
tinctness of the plant as a genus for the 4nadyomene. : 
. Harvey has also sent me some specimens of an Anadyomene 
from West Florida and from Bermuda, which certainly show that 
this species is variable in the size and form of the cells; and there is 
one speeimen which seems in his opinion to combine the two species. 
He says the soft rigid state of the frond depends partly on the age of 
the specimen, partly on the length of time it is steeped in fresh water, 
and partly on the manner of drying. “The Key West plants, which 
are as common as Ulva are here, also differ greatly in the length of 
the joints of the generating filaments in different parts of the plant." 
Amongst the specimens which Dr. Harvey has so kindly sent me is 
one named * Anadyomene (?) Leclancheri, Decaisne,” from the Sooloo 
Archipelago. This plant shows that the characters which I have given 
to the tribe must be modified, and that the genera should be arranged 
into two groups, the first containing the genera I have described; they 
have the interspaces between the generating filaments filled up with 
smaller cells, making a continuous frond. The second has part of the 
interspaces between the filaments void, forming a netted frond, pierced 
with roundish holes or spaces between the meshes. En 
The’ Alye@ of this group, though it has the netted frond, as in 
Microdictyon, cannot be confounded with that genus, as the mesh is 
formed of many different-sized and very variously-disposed cells, some 
