244 SEAWEEDS 
seas, the Corallines have a much wider range than the 
animal corals, and occur in considerable numbers in 
the colder regions of the ocean. On British shores, 
Corallina, Jania, Lithothamnion, Lithophyllum, Melo- 
bestia, and a very minute form, Schmitziella (incrusting 
Cladophora pellucida), represent the family with a fair 
number of species. 
The stony incrustation extends to all parts except 
the reproductive organs. Tetraspores, antheridia, and 
carpospores, are all formed in special conceptacular 
bodies (Figs. 84 and 85). In the flat encrusting 
forms these conceptacles appear as minute, wart-like 
outgrowths from the sterile part of the thallus; in 
Corallina they occupy the summits of the branches; 
and in Amphiroa they are lateral. In Lithothamnion 
these conceptacles are eventually overgrown by the 
increasing growth in thickness of the thallus, and in 
breaking down the stony substance they may be met 
with as small cavities representing the conceptacles 
of earlier periods of growth. 
The carpogonial branches occur, together with 
numerous auxiliary cells, in special fertile portions of 
the cortex. The auxiliary cells are joint cells of 
peculiarly differentiated thallus filaments. On the 
fertilisation of the carpogonium all, or nearly all, the 
auxiliary cells near it become fused with it by means 
of the ooblastema filament, forming a large “ conjuga- 
tion cell.” From its periphery minute gonimoblasts 
arise, bearing chains of carpospores. The cystocarp 
is here, therefore, a kind of syncarp, since it results 
from the combination of numerous auxiliary cells 
and their products into one common definite fruit, 
