Howe: PHYCOLOGICAL STUDIES 505 
(20-35 mm. max. vs. 10-13 mm.) segments, more patent or sub- 
divaricate branching, and larger more vacuous medullary cells. 
Gracilaria (?) peruana Picc. & Grun. was briefly described and 
thus far appears to be known only from the original collection, 
from which, through the courtesy of Professor G. B. De-Toni, we 
have been able to examine a portion of a tetrasporic specimen. 
Gracilaria Vivesit differs from it in being of a coral-red or rose 
instead of a sordid green or lurid brownish color, in being regularly 
dichotomous instead of di-polychotomous, in having segments that 
are subquadrate or cuneate-oblong rather than subcuneate-linear 
and patent or subdivaricate rather than subparallel, and in having 
a cortex that is 1-3 instead of 3 or 4 cells thick in the mature parts 
and whose outer walls are 13-28yu instead of only 4-6y thick. 
The medullary cells in G. peruana are large and vacuous, much as 
in G. Vivesii, but are even larger, sometimes showing a maximum 
diameter of 650p in a cross section of the thallus. The transition 
from these large medullary cells to the small cells of the cortex 
is a little less abrupt than in G. Vivesii. The thallus of G. peruana 
is rather thicker than that of G. Vivesii, attaining a maximum 
thickness of about 1 mm. in the older parts of the fragment seen; 
it scarcely adheres to paper. 
Rhodymenia peruviana J. Ag. is doubtless deserving of mention 
in connection with Gracilaria Vivesii. The writer’s present 
knowledge of this Peruvian species is based chiefly on Agardh’s 
description and a photograph of the original specimen which has 
been accessible through the kindness of Professor O. Nordstedt. 
Its mode of branching and general habit do not suggest the Baja 
California plant, and Agardh’s allusion to sori in connection with 
the tetrasporangia would seem to indicate that Rhodymenia 
peruviana does not belong in Gracilaria. In size and in habit, 
so far as can be judged from a photograph, Rhodymenia peruviana 
is not very different from Gracilaria (?) peruana, yet Piccone and 
Grunow, having before them Agardh’s description of the color 
and consistency of R. peruviana and having before them also the 
cystocarps and scattered tetrasporangia of their own Peruvian 
plant, were apparently quite right both in considering their plant 
different from Agardh’s and in referring it to the genus Gracilaria. 
