ON THE STRUCTURE OF SORANTHERA. 479 
On the Structure and De ment of Soranthera, Post. & Rupr. 
By Erurn Sara Baros. (Communicated by Gronak 
Murray, F.R.S., F.L.S.) 
[Read 5th May, 1898.] 
(Prates 23 & 24.) 
THE genus Soranthera (Pheophycee) was established by Postels 
and Ruprecht with one species, S. ulvoidea, in their ‘ Illustra- 
tiones Algarum, 1840, p. 19. In the generic diagnosis the 
structure is said to be that of Ulva, while the fructification re- 
sembles Punctaria. S. ulvoidea is described as parasitic on 
Rhodomela Larix, and though the word “ parasitic " was probably 
used in the sense of “epiphytic,” investigation proves that the 
original word was correct, as will be shown. A figure is given 
of a small group of unilocular sporangia and paraphyses. 
The next mention of the plant is made by Endlicher (* Genera 
Plantarum, Suppl. iii. 1843, p. 25), where he condenses the 
original description, but does not omit the word “ parasitica.” 
However as he calls Myriotrichia also “ parasitic,” this points 
to a confusion of terms. 
Prof. J. G. Agardh (Spes. Gen. et Ord. Alg. vol. i. p. 120, 
1848) quotes the original diagnosis of Postels and Ruprecht, 
and places the genus as one of doubtful affinity under Dictyote. 
Kützing (Spec. Algarum, 1849, p. 566) follows Prof. Agardh. 
In 1850 Ruprecht, one of the joint authors of the genus, in 
his * Alge Ochotenses, pp. 179, 180, gives a short account of 
the development of S. ulvoidea. Since he speaks of making his 
investigations with a lens, they are not, as might be expected, 
exhaustive. At some time an idea had evidently prevailed that 
S. ulvoidea was only a form of Ulva (possibly U. fusca), and that 
the sori were a species of Myrionema. Ruprecht here shows 
that this idea must be abandoned, if only on account of the 
regular distribution of the raised patches of fruit. He recognizes 
the connection between Soranthera and Asperococcus, and speaks 
of the plant, in a wide sense, as Asperococcus ulvoideus. 
It is interesting to note, in view of the development of Soran: 
thera, to be described later, that Ruprecht says it grows mivglec 
With Leathesia tuberiformis on Rhodomela. 
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LINN. JOURN.—BOTANY, VOL. XXXIII. 20 
