210 SEAWEEDS 
The Geographical Distribution of the family is 
widespread, Chantransia, Nemalion, Helminthora, 
and Helnvinthocladia being represented in British 
seas, while Ziagora is confined to tropical and warm 
regions of the sea, occurring however as far north 
as the Mediterranean. 
Chetangiew. 
The gonimoblast is a convex, or concave, or spread- 
ing tuft of branched filaments, of which the terminal 
cells produce carpospores. The main difference 
between this family and the last is in the fact that 
the gonimoblast is immersed in the thallus and 
always enveloped in a special, thick, cellular fruit 
wall. The gonimoblast originates from one side 
only of the carpogonium as in Chantransia ; at all 
events this is the case with Scinaia, in which it has 
been carefully observed. 
Scinaia has a dichotomously branching thallus, 
consisting of a central axial tissue, from which there 
issue at right angles radiating, loose dichotomous 
filaments, constituting an intermediate tissue between 
the axial and peripheral tissues, the latter being com- 
posed of large colourless cells, with small ones filling 
up the spaces between them. Externally it is 
gelatinous. The cystocarps occur immediately be- 
neath this peripheral tissue. Chetangiwm has a 
strong, vigorous, irregularly branched thallus with 
foliar expansions, often transformed into air-floats. 
Galaxaura and <Actinotrichia have more or less 
encrusted peripheral tissues with slight annulate 
