an annual plant, whereas the other exists for several years.”
— Carm.
A microscopical examination of these two plants will not
only make it evident that the two are specifically distinct,
but also most probably generically so.
Section ii. R a p h id ia Carm.
Char. Frond gelatinous, subglobose, bullated. Filaments
few, fagelliform, simple, moniliform within, scattered
through the gelatine, or radiating from a central point.
1. R a p h id ia angulosa Hass.
Plate L X IV . Figs. 1. 4.
Char. Fronds gregarious, roundish, gelatinous, hollow, o f a
bright chestnut colour when recent, changing to dark olive
in drying. Filaments large, often produced into a long
and curved setigerous point. Sheath hroad, often angular.
Rivularia angulosa Roth, Harv. in Hook. Br. PI. p. 394.;
and in Manual, p. 153. Ulva pruniformis, F . B. t. 968.
Raphania natans Carm. MSS. cum icone.
Hah. Attached to aquatic plants in ponds and still waters,
or fioating on tlie surface, A p p in : Captain Carmichael.
In a pond on the common east of Lewes and Burwash
Road, near Fasten G re en : W. Borrer, Fsq. Swansea :
Air. Ralfs. Cheshunt Marshes : A. H. H. Near Cascades,
CO. Antrim : Mr. Moore.
“ Fronds gregarious, often confiuent, one fourth to three
fourths of an inch in diameter, roundish, gelatinous, vesicular,
and when detached, rising to the surface of the water with
the velocity of an air-bubble. Filaments at the distance of 4
or 5 diameters from each other, radiating in all directions from
the centre of the vesicle; rising from a colourless globule,
infiatcd for about one-third of their length, thence tapering to
a long slender often curved point. Internal mass moniliform,
occupying about one half the diameter of the infiated part of
the filament. Colour pale chestnut, inclining to olive.” —
Carm.
2. R aphidia viridis Hass.
Plate L X IV . Figs. 3. 2.
Char. Frond very mucous, soft. Filaments small, elongated.
Sheath not evident.
fl marginata. — Y'Aa\a.<pa.t% rather smaller. flixQaih. evident.
Hab. Near Manchester: Mr. Sidehotham. Aberdeen:
Dr. Dickie.
This Raphidia is very distinct. I t was sent me by Mr.
Sidehotham of Manchester put up in fluid. The filaments
are not one half so large as those of R. angulosa, but much
longer; the sheath in it could not be detected. In the variety
fl the sheath was quite apparent, and I at first was induced to
regard it as altogether different: it is safer however to consider
it merely as a variety of R . viridis, or as that species in its
perfect condition, the sheath in the specimen sent by Mr.
Sidehotham, and which had been put up some time in fluid,
having probably become decomposed.
Section iii. L ith o n em a Hass.
Char. Fronds indefinite, truly ramose. Bases o f the filaments
not manubriated. Filaments petrified.
Derivation. From \ l6 o s , a stone, and vyga, a thread.
1. L ithonema calcareum Hass.
Plate L X V . Fig. 2.
Char. Fronds large, orbicular, convex, afterwards aggregated
into a broad spongy crust zoned within, at length petrified.
Filaments slender, adherent, and dichotomously branched.
R . calcarea Sm., F . B. t. 1799.; Harv. in Hook. Br. Fl.
p. 3 92.; also in Manual, p. 150.
Hab. On rocks and stones in streamlets and the borders of
subalpine lakes.