424 
THE SEAWEEDS 
growth peripheral from the ends of the filaments of the basal layer; 
sporangia tetrapartite, scattered between the erect filaments in nemathecial 
groups or in crater-like conceptacles; spermatangia in tufts on the ends 
of the erect, paraphysal filaments; carpogenic branches scattered or in 
nemathecia, short, lateral on paraphysal filaments; after fertilization the 
carpogonium fuses with an intermediate cell in the carpogenic branch, from 
which ooblast filaments go out to auxiliaries formed laterally at the bases 
of other paraphyses ; gonimoblast masses small, scattered, formed from the 
fertilized auxiliary cells. 
Peyssonnelia Decaisne. 
Family CRUOR1ACEAE Kylin 1928. 
Plants forming expanded crusts with marginal growth, adhering by the 
under surface, above forming erect, crowded filaments lightly united; 
zonate or irregularly tetrapartite sporangia known; carpogenic branches 
short, the ooblast filaments developing directly from the simple or divided 
carpogonium to make vegetative unions with various assimilatory filaments, 
and ultimately to give rise directly to the gonimoblasts, of which all cells 
are converted to carposporangia ; true auxiliary cells absent. 
Family CORALL1NACEAE (Gray) Harvey 1853. 
Plants with a thin basal layer which may develop into a massive cal- 
careous crust or a system of rigid branches, or from which may arise 
solitary or scattered, erect, slender-branched, jointed axes, the segments 
showing the multiaxial type of structure with chromatophores in the peri- 
pheral cells, and the whole calcified except the intervening flexible joints; 
reproductive organs in conceptacles with a definite perithecium-like wall, 
sunken in the crust, or terminal on lateral enlarged branches; tetra- 
sporangia zonate, often associated with sterile paraphysal filaments; sper- 
matangia on short filaments crowded in conceptacles; carpogenic branches 
usually three-celled, in the central part of the cystocarpic conceptacle, the 
lower cell acting as the auxiliary; after fertilzation union of the carpo- 
gonium with the lower cell of the carpogenic branch occurs and then by 
ooblast filaments with the auxiliary cells at the bottom of other branches, 
after which general fusions occur, so that the carposporangia ultimately 
arise from the large fusion cell. 
This family includes practically all the calcareous Rhodophyceae. 
Lithothamnion Philippi. Melobesia Lamouroux. Mastophora Decaisne. 
Lithophyllum Philippi. Goniolithon Foslie. Amphiroa Lamouroux. 
Cheilosporum Areschoug. Jania Lamouroux. Corallina (Tournefort) 
Lamouroux. Arch eolith othamnion Eothpl. 
Family GRATELOUP1ACEAE. 
Plants of this family belong to the “fountain” type. Each segmented 
cell near the growing point of the central filament forms outwardly a 
branching system of short filaments, which close over and form the cortex. 
