1^25] Setchell-Gardner : Melanophyceae 507 



G. Marchantae differs from G. Johnstonii in the character of the 

 basal penetrating portion, the former having few narrow filaments 

 and the latter having a dense, copious base. Two or three cells in the 

 lower part of the free filaments are usually asymmetrical in G. Mar- 

 chantae and not in G. Johnstonii. Neither species has hairs nor any 

 indication of having had them, a prominent character as figured bj^ 

 Tliuret and Bornet in Etudes Phycologiques, pi. 7, figs. 2-6, for 

 Elachista pulvinata and mentioned by Yendo as " paraphysibus pau- 

 cioribus" in Myriactis Sargassi (Novae Alg. Japon., 1920, p. 3). 

 G. Marchantae is close to G. pulvinata in the character of the basal 

 penetrating portion. G. Johnstonii in general resembles G. monili- 

 formis but is much smaller throughout. 



FAMILY 6. LEATHESIACEAE pam. nov. 



Thallus thick, carnose, expanded on the substratum and solid or 

 irregularly globular and hollow, arising from a flattened, monostro- 

 matic (?) persistent or evanescent disk; inner cells large, colorless, 

 loosely parenchymatous of di- to trichotomous filaments, outer colored, 

 in anticlinal rows, generally decreasing in size from within outwards, 

 held together, at least loosely, by the surrounding jelly ; zoosporangia 

 and gametangia with loculi uniseriate or nearly so, both immersed 

 among the external anticlinal rows present and borne on the same or 

 similar plants; epiphytic or saxicolous. 



Corynophlaeceae Oltmanns, Morph. und Biol, der Alg., 1922, p. 23. 



As will be made apparent later, it seems most desirable to restrict 

 the family Chordariaceae to the genus Chordaria, as typified by 

 C. flagelliformis, an erect branched plant with distinct elongated 

 axis and lateral branches of limited growth, with subapical terminal 

 meristem, not trichothallic in the same degree as in the ^giraceae 

 and with only the unilocular zoosporangia thus far known, suggest- 

 ing the strong probability of a microscopic gametophyte. The 

 ^giraceae are more or less elongated, simple or branched plants, with 

 strongly trichothallic apical meristems, and both zoosporangia and 

 gametangia borne on macroscopic plants. The Corynophlaeaceae of 

 Oltmanns (1922, p. 23) includes the genera Cylindrocarpus, Micro- 

 coryne, Strepsithalia, Corynophlaea, Myriactis, and, presumably, 

 Leathesia, although Oltmanns might be suspected of merging {loc cit., 

 p. 26) Leathesia (Gray, 1821) in Corynophlaea (Kuetzing, 1843). We 

 have referred Myriactis (Gonodia.) to the Elachisteaceae because of 

 its close resemblance to Elachistea. Cylindrocarpus microscopicus 



