124 ALLAN HANCOCK PACIFIC EXPEDITIONS VOL. 3 



maria Stack. (Tent. mar. crypt., 54 (1809) ) was rejected. The genus as 

 Agardh understood it has been accepted almost to date. A modification of 

 his arrangement of species (J. G. Agardh, Epicr., 328-332 (1876)) has 

 not been attempted since his time, even though a very considerable num- 

 ber of new species have been described (cf., e.g., De Toni, Syl. Alg. IV, 

 11:509 (1900),— Kylin, Die Florideenord. Rhodymen., 1-48 (1931),— 

 et al.). 



After an investigation, both macroscopical and microscopical, of all 

 the immediately available specimens referable to the genus Rhodymenia, 

 it has seemed best to follow Agardh, but to institute further a new section 

 Pertusae and to reduce the genus Dendrymenia Skottsb. (Bot. Ergeb. 

 schwed. Exped. nach Patagon. IX Rhodophyceae, p. 16 (1923)) to 

 subgeneric status. Agardh's method of separating the sections on tetra- 

 sporic characters has been carried a little further and, based on the oc- 

 currence of tetraspores, scattered or in sori ; and, under the latter, whether 

 the cortex is nemathecioid or nonnemathecioid, the new section Pertusae 

 is established as equivalent with Agardh's sections Palmatae, Palmettae, 

 and Clinophora. 



In establishing Dendrymenia as a subgenus account has been taken 

 of the branching habit of the stipe and of the occurrence of stolons. The 

 specimens included are those which show a sympodial branching of the 

 erect stipe in addition to the production of decumbent branches. In sec- 

 tions Palinettae and Clinophora branching of the stipe frequently occurs 

 to produce stolons, and in cases in which the stoloniferous region of the 

 stipe gives rise to blades through the branching of these stolons, the dis- 

 tinction from Dendrymenia may be very difhcult to interpret. This con- 

 dition seems to make a generic separation undesirable but does allow the 

 suggestion of a fifth section for the genus — Dendrymeniae. 



The genus embraces about 54 species, of which 14 are described in 

 this article. Of the total number, the occurrence of tetraspores, which are 

 highly important in distinguishing the members from one another and in 

 arranging them in the sections, is unknown for about 26 species. Cysto- 

 carps are unknown in even a larger number, and thus the arrangements 

 proposed here are only suggestive and are subject to change at any time 

 upon the discovery of new and pertinent facts. Several new species are 

 provisionally described from sterile material ; others, from a single speci- 

 men. These, like many of the already described species, ai'e incomplete, 

 and their determination even as to the genus may be regarded at present 

 as no more than tentative. 



