G. SERTULARIA. 
81 
SERTULARIA. 
A plant-formed Polypidom, branching; stem 
usually flexuous or in zigzag ; cells alternate. 
The form of the Polypidoms which I have united in 
the family of theSertularias varies considerably : some 
have their branches dispersed, and form almost pani- 
culated stems ; there are some whose stem is upright 
with flexuous branches ; a great number have their 
branches straight upon a flexuous stem : finally, there 
are some whose divisions are dichotomous and diver- 
gent, and which break, when dry, on the slightest at- 
tempt to bend them. 
The substance of the Sertularias is horny-mem- 
branous ; with sometimes a slight cretaceous incrus- 
tation on the lower part of the Polypidom. 
Their colour, in general agreeably shaded, does 
not equal the Corallines in brilliancy of tints. This 
colour varies from white to a lawn, from rose-colour 
to a tarnished green. 
They greatly differ in size ; some scarcely reach- 
ing a centimetre, while others raise their branches 
many decimetres high. 
They are found in all seas, and in all latitudes. 
FIR. 
1. Sertularia abietina . Cells oval, tubular, 
with a border entire ; bulging towards the stem. 
European seas. 
PECTINATED. 
2. Sertularia pectinata . Base or root branch- 
Cor. 
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