180 Collins and Howe: Species of Halymenia 



0.6 mm. in diameter, and to the naked eye they sometimes look a 

 little as if they might be cystocarps. A filamentous short-celled 

 Rhodophyceous endophyte sometimes forms dense subglobose or 

 irregularly lobed glomeruli in the medulla and these also may 

 have the superficial appearance of being cystocarps of the Haly- 

 menia. 



Halymenia pseudofloresia, like H. bermudensis, is commonly 

 found in an unattached condition, and possibly the absence of 

 cystocarps is in some way associated with this fact. The senior 

 author has noted that Delesseria sinuosa and certain other mem- 

 branaceous Rhodophyceae are commonly sterile when found in 

 places where they have apparently been vegetating for some time 

 unattached. 



Specimens of Halymenia pseudofloresia, with occasional ex- 

 ceptions as to parts of the old fronds, adhere firmly to paper 

 when dried under pressure, 



Halymenia echinophysa sp. nov. 



Thallo pallido-vinaceo vel lilacino, membranaceo, gelatinoso, 

 125-200 M crasso (madefacto), circumscriptione suborbiculari, 

 10-18 cm. diam., profunde, irregulariter vel subpalmatim lobato, 

 lobis irregulariter obovatis vel suborbicularibus, marginibus 

 sinuato- vel eroso-dentatis; medulla frondis subvacua vel laxe 

 filamentosa, filamentis homogeneis, 10-14 fi diam. ; strato cortical! 

 gelatinoso translucido, submonostromatico, cellulis superficialibus 

 ovoideis, subglobosis vel ellipsoideis, 4-8 n diam. max., 5-10 m inter 

 se distantibus, in membrana communi horizontaliter vel verti- 

 caliter positis, parietibus exterioribus (vel membrana superficiali 

 extra-cellulari) 10-18 ix crassis; strato subcorticali 2-4-stromatico, 

 cellulis arete anastomosantibus, ovoideis, ellipsoideis, vel interdum 

 complanatis, extimis 6-10 m diam., intimis 25-65 /z diam. max., 

 nonnullis subglobosis, 80-180 ^ diam., echinato-stellatis, in me- 

 dullam protrudentibus, processubus 15-40, subrigidis, subspines- 

 centibus, munitis. 



Species H. adinophysae M. A. Howe proxima, sed differt thallo 

 minore, crassiore, magis lobato, non-nitente, membrana super- 

 ficiali communi duplo crassiore, cellulis superficialibus inter se 

 duplo distantioribus, filamentis medullaribus dimidio minus 

 crassis et minus regulariter et minus manifesto capitatis in strato 

 subcorticali abientibus, cellulis intimis strati subcorticalis saepe 



