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CLASS I. — ORDER II. 
ing ; stem simple, pinnated ; branches very long ; cells 
very small, with a border entire ; ovaria inclining to 
oval, and rather large ; colour deep brown ; size about 
a decimetre. 
THREE-TOOTHED. 
3. Sertularia tridentata. Base branching ; stem 
straight and pinnated ; pinules diverging ; cells with 
three teeth on their border, the opening oblique ; co- 
lour yellowish ; height from four to six centimetres. 
Australasia. 
TAMARISK. 
4. Sertularia tamarisca. Cells tubular, with 
three or four teeth on the border ; ovaria compressed 
as if truncated, with a thorn at each side. 
Northern and Mediterranean seas, &c. 
FERN. 
5. Sertularia jUicula. Stem flexuous ; branches 
articulated ; cells tubular at the summit. 
European seas. 
TOOTHED. 
6. Sertularia dentata. Stem branching; cells 
pyriform, with a toothed border ; ovaria oval, border 
of the opening blackish; height two centimetres. 
Bay of Cadiz. 
ELONGATED. 
7. Sertularia elongata. Base branching; stem 
usually simple, pinnated, but rarely bipinnated ; 
branches situate at the upper part of the stem ; cells 
approximate, and small, with ciliated borders ; ovaria 
oval, truncated at the summit, compressed, with tw r o 
