110 
Dusiin NatTurRAt-History Society. 
March 10th, 1854.—Dr. Croker, M.R.1.A., President, in the chair. 
Fructification of the Genus Desmarestia. 
Mr. Gilbert Sanders read the following paper “On the Fructi- 
fication of the Genus Desmarestia.” 
“ At the request of my friend Dr. Allman, I beg to present to the 
Dublin Natural History Society a short description of the fructification 
of Desmarestia as observed in the species D. ligulata. Dr. Harvey, 
in both editions of his ‘Manual’ and in the ‘ Phycologia, as well as 
every other Algological authority | am acquainted with, records the 
fructification of Desmarestia as unknown. I was recently engaged in 
microscopically examining the structure of several specimens of Des- 
maresti ligulata, when I observed some very minute brown spots on 
the pinna I had under the microscope, which were resolved by a. 
higher power into small defined tubercles, through the pellucid walls 
of which I saw assemblages of angular spores of the usual pink 
colour, of the spores of the Floridez. Further examination showed 
that these tubercles were pretty freely distributed over both surfaces 
of the pinna, on the margins as well as on the flat surfaces; those 
seen on the margins being in profile showed a hemispherical outline, 
the greater part of which projected beyond the margin. I have no 
doubt of these tubercles being the fruit, and that they are to be 
regarded as conceptacula and superficial. I examined pinne from 
two other specimens of D. ligulata, which I had in my possession 
some years ago, and in both I noticed traces of the same appearance 
of fruit, but not nearly so distinct as those on my first specimen. In 
these last the capsules and spores appeared to have discharged their 
endochrome, and which is very probable, as this genus is very im- 
patient of fresh water, or even exposure to the air, decomposition 
commencing almost immediately after they are removed from the sea. 
If the mode of fructification is to guide us in the arrangement of the 
genera under orders, I conceive Desmarestia should be removed from 
the order Sporochnacee to Dictyotacee, as the fructification I have 
observed in D. ligulata is much more conformable to the latter order 
than to that of the former. I have not as yet perceived any symptom 
of fruit either on D. aculeata or D. viridis, but the scattered single 
spores so very abundant on Mr. Sawer's late important addition 
