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to British Botany, Desmarestia pinnatinervia, cannot but be the 
fruit of that species. These spores have the same pink colour as 
those of D. ligulata, but, instead of being in capsules, they appear on 
every part of the frond like strings of beads or chains. I think it not 
improbable that young spring plants of the two other species, acu- 
leata and viridis, will reward careful examination by a discovery of 
their fructification, and I would recommend search to be made among 
the byssoid fibres with which the young plants are clothed. 
“T take this opportunity to exhibit some specimens of Desmarestia 
pinnatinervia, for which I am under obligation to Mr. William Sawers, 
of Londonderry, to whom belongs the honour of adding it to the ma- 
rine Botany of our country. Mr. Sawers sent specimens of his plant 
to the meeting of the British Association at Hull, and to most of our - 
best algologists, some of whom pronounced it a mere variety of a 
Laminaria. At length specimens reached Dr. Montagne, of the 
French Institute, who recognised it as his D. pinnatinervia, a descrip- 
tion and figure of which he gave in the ‘ Annales des Sciences Natu- 
relles’ for 1842, vol. xviii. As there are some differences between 
the appearances of the Spanish plant, as described by Dr. M., and 
those found by Mr. Sawers, I will refer to a free translation which I 
have made of the article in the ‘ Annales.’ 
“¢Ts it truly a Desmarestia? That is a question not easily decided 
in the absence of any fructification. M. Aghardh is inclined to 
believe it is to that genus we should refer it. This Alga requires care- 
ful description, because it has a perfect resemblance to Laminaria 
debilis, collected on the coast of Corsica by my friend M. Solierol. 
The only differences which [ have found, though essential differences, 
and which separate our plant from those with which I have compared 
it are — first, the presence of a well-defined stipe, about four or five 
millimetres long—secondly, a midrib, which traverses the entire length 
of the frond, and from which nervures issue to the right and left at 
the distance of five to ten millimetres from one another, forming with 
the midrib angles of about 24°. _—_ All these nervures, though strongly 
marked, are of the greatest tenuity. The form of the frond is 
obovate, fourteen millimetres long by eight in width at the widest part, 
which is the summit. It has the same delicate tissue as Laminaria 
debilis. If it is a Desmarestia, as all believe it to be, we must con- 
sider the frond as formed by the fusion of the opposing pinnules, 
which will represent the nervures.’ 
