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 Pice. & 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 Vivesii 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 13-28/z instead of only 4-6^ 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 650/z 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 I 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. 



