1 2 
“The differences which I find between the Spanish plant as described 
by Dr. Montagne, and the specimens of the Irish plant supplied by 
Mr. Sawers are:—The Spanish plant is dentated at the margin, ob- 
ovate, and widest at the summit; Mr. Sawers’ specimens are entire 
at the margin, very slightly waved, lanceolate, and widest about one- 
fourth of the length of the frond from the base, tapering thence 
towards the summit. The proportions of length and breadth of the two 
plants are very dissimilar; however, I am inclined to regard them 
at present as identical, merely altered by the circumstances of climate. 
It is singular, that although the figure given in the ‘ Annales’ exhibits 
an appearance of dots, Dr. Montagne has made no mention of chain- 
like series of spores, such as are contained in the dots in Mr. Sawers’ 
plants. I imagine that from these spores on our Irish specimens, the 
exotic ones have them also. By some it has been doubted if the 
plants taken at Lough Foyle are indigenous to that coast, but have 
supposed them to be stray waifs, brought from more temperate 
regions by tides and currents. I cannot subscribe to such ideas from 
the fact of Mr. Sawers having found fronds of his Desmarestia in tole- 
rable abundance during a large portion of last year (1853) even up to 
near Christmas, and as Desmarestia undergoes decomposition so very 
rapidly when dead, I cannot believe it possible those fronds which we 
see here in excellent preservation, could have been knocking about 
on the ocean for months: I therefore conclude they grew not far 
from the spot where Mr. Sawers found them. In conclusion, I would 
wish to remark on the doubt implied in Dr. Montagne’s paper as to 
the Alga in question being a Desmarestia. The structure certainly 
agrees with that of D. ligulata. As my specimens were quite dry when 
they reached me, I could not determine if the single-jointed tube men- 
tioned by Dr. Harvey as traversing the fronds exists in pinnatinervia ; 
should it be found there I have no doubt that it will appear in the 
nervures and midrib. Although the question is one of much interest 
to the algologists, and I look forward with expectation that Dr. 
Harvey will investigate the subject on his return, and clear up existing 
doubts; I think it very evident that if the pinnatinervia be a Des- 
marestia, and if the tubercles I have observed on ligulata be the true 
fruit, then Dr. Harvey will have to construct the genus anew, for the 
diagnosis does not meet the existing facts.” 
Mr. Sanders gave very clear explanations of his several micro- 
scopical examinations, which he illustrated by handsomely coloured 
diagrams. He was clearly of opinion that he had detected the spores 
indicative of a true state of fructification. 
