344 
THE SEAWEEDS 
MUELLERENA Schmitz. 
Fronds erect, terete, abundantly branched in one plane, lateral branches 
regularly distichous, alternate, crescentic or symmetrically branched. 
Central axis articulate, thick ; ramuli covered with whorls of free ramelli 
in fours, at length densely corticated externally by rhizoids, becoming 
shortly pilose. Cystocarps minute, impersceptible, situated in lower parts 
of lateral branches on the fertile verticils, all involucrate with verticillate 
ramuli. Gonimoblasts evolved successively from many round gonimolobes. 
Tetrasporangia sparse, terminal on ramelli of verticillate branches, trian- 
gularly divided. 
Muellerena Wattsii (Harv.) Schmitz. 
= Crouania Wattsii Harvey. 
Frond cartilaginous, thickly corticated throughout, opaque, dichotomous, 
bi-tri-pinnate ; pinnae and pinnules alternate, close, horizontally spreading, 
whorled at the nodes with minute, dichotomo-multifid, four ranked, articu- 
lated, mucronate ramelli ; tetrasporangia globose, sessile. Frond 4 cm. to 
Fig. 170 . — Muellerena Wattsii: a, plant; b, one of the 
pinnules, whorled with ramelli; c, cross- 
section of the pinnule, through one of the 
whorls; d, part of a ramellus; e, a tetraspore 
from the same; f, cross-section of a branch. 
(After Harvey.) 
