PDF file (text) - Cryptogamic Botany Company

88
THE MARINE ALGÆ OF NEW ENGLAND.
R. CLAVATA, (Carm.) Crouan, Florule du Finistère. (Myrionema clavaturn, Carm., in
Phyc. Brit., Pl. 348.)
Fronds thin, forming closely adherent crusts or coriaceous expansions, at first
orbicular and afterwards irregular; paraphyses clavate, rather uniformly diffused
over the frond; unilocular sporangia pyriform, .06-7 mm broad by .15-.18 mm long,
attached to the base of the paraphyses.
On stones and wood work
Eastport, Maine; Wood’s Holl, Maiden, Mass.; Europe.
A small species, whose position is, doubtful. It was placed by Harvey in Myrionema, from the typical
species of which it differs in having a frond composed of several layers of horizontal cells. By Crouan it
was placed in Ralfsia, but the erect filaments rather resemble the paraphyses in Myrionema. In short,
the species may be said to be a Ralfsia with diffuse fructification and slightly developed frond, or a
Myrionema with an excessively developed basal portion. American specimens resemble perfectly the
No. 56 of Crouan’s Algues Marines du Finistère. The alga described by Areschoug under the name of
Lithoderma fatiscens bears a striking resemblence [sic] to the present, species. The species is much
smaller and thinner than R. verrucosa, not exceeding on the average .15 mm in thickness, and covers
stones and wood work at Eastport, sometimes in company with R. verrucosa. Further inquiry will
probably show that the plant is common along the whole coast.
FAMILY ASPEROCOCCEÆ.
Fronds tubular or compressed, usually simple, occasionally branched; fructification
in external scattered sori, composed of cylindrical few-celled paraphyses and
spherical unilocular sporangia.
ASPEROCOCCUS, Lam.
(From asper, rough, and κοκκος [kokkos], a berry.)
Fronds olive-brown, simple or branched, hollow, composed of a few layers of cells,
those of the interior being larger and colorless, those of the surface smaller and
colored; fruit external, scattered in spots (sori) over the fronds; sori composed of
paraphyses and unilocular sporangia, which are formed from the superficial cells of
the fronds; paraphyses numerous, cylindrical or club-shaped; unilocular sporangia
globose, sessile between the paraphyses; plurilocular sporangia unknown; hairs
tufted, arising from the superficial cells; growth of fronds basal.
The genus Asperococcus is distinguished by the external scattered fruit, consisting of paraphyses and
unilocular sporangia. In the Nereis Am. Bor. it was placed by Harvey in the order Dictyotaceæ, but the
fructification in that order is now known to be very different. The genus comprises a small number of
species, which are widely diffused, although as yet only one has been found on the New England coast.
The Asperococci resemble, to a certain extent, species of Phyllitis and Scytosiphon, but are easily
distinguished by the fruit, which is almost always present. Plurilocular sporangia are unknown in the
true Asperococci, and the old A. sinuosus, which is found in Florida and California, is considered by
Bornet to belong to the genus Hydroclathrus, which has plurilocular sporangia of the same type as
Phyllitis and Scytosiphon. A. compressus