APPENDIX OF NEW SPECIES 
DISCOVERED SINCE THE PUBLICATION OP THE “PHYCOLOGIA 
BRITANNICA.” 
OLIVE GROUP. 
Family II. SPOROCHNACE^. 
DESMAEESTIA DEESNAII. 
Colour. Pale fawn-brown, becoming a pleasant olive-green when dry. 
Substance. Firmly membranaceous ; somewhat horny when fresh ; never becoming very soft. 
Character of Frond. Flat, leaf-like, with an evident but thin midrib throughout, and side 
veins ; margins slightly indented. When perfect, oppositely branched (if the phrase 
be allowed) with leaf-like fronds of the same character : the whole plant consisting 
of leafy formations, springing from each other. 
Measurement. Specimen in Trinity College Herbarium (Dublin), 10 inches long by 2 wide. 
But Mr. Sawers describes others as 18 inches long, breadth 3. 
Fructification. Not ascertained. 
Habitat. Moville Bay, Co. Donegal, 1853. Mr. Wm. Sawers. 
By Agardh, and also by Dr. Harvey, this plant is considered as only an extravagantly 
wide form of D. Ugiilata; but no one who has not seen intermediate specimens can easily 
believe this. Yet, in the tapering to both ends of the so-called branches of the common 
forms of D. ligalata, a tendency to leaf- like formation may be observed; the branchlets espe- 
cially, resembling small libless leaves. On the other hand, the “ obscure midrib tow^ards the 
base” of Z>. ligulata indicates an inclination to that formation also. Any one interested in 
the subject will find the growth oi Desmarestia described in Dr. Harvey’s Nereis Boreali- 
Americana, vol. i. p. 77. 
Family V. CHOEDARIACE^. 
LEATHESIA CRISPA. 
Colour. Olive -brown. 
Substance. Always firm and solid. 
Character of Frond. More or less globose ; forming small tubers upon the fronds of other 
algae. The internal threads which compose it, densely crowded. Tubers running 
together in irregular patches as their growth proceeds. 
Measurement. Tubers from to ^ of an inch in diameter ; patches an inch or more. 
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