182 Collins and Howe: Species of Halymenia 



filaments in the subcortex, and in the often much larger, more 

 numerously and more echinately branched stelliform cells of the 

 inner subcortex. 



From H. hermudensis Collins & Howe, to certain forms of which 

 it bears a superficial resemblance, it differs in being much more 

 gelatinous, in the much thicker surface jelly or outer walls of the 

 superficial cells (10-18 /i vs. 2-4 ^ thick), in the more generally 

 monostromatic cortex, in the more widely spaced (5-10 /x vs. 2-3 /x) 

 protoplasts of the superficial cells, in having a medulla that is 

 filamentous and homogeneous instead of showing a system of 

 substellate ganglia with refringent specialized protoplasts, and in 

 the presence in the inner subcortex of cells that are 80-180 {x in 

 diameter with 15-40 subspinescent processes, while the inner cells 

 of the subcortex of H. hermiidensis are 13-25 ix in diameter and 

 have no obvious appendages. 



When the enlarged echinate-stelliform cells of the inner cortex 

 are detached, some of their numerous sharp-pointed processes 

 show apices that look as if they had been free from all cell con- 

 nections, but most of them show at the apex traces of a septum 

 to which they have narrowed down and at which point they have 

 been disjoined from their former cell connections. The proto- 

 plasts of these large echinate cells are similar to those of their 

 neighbors or are more vacuous, wherein they differ greatly from 

 the substellate medullary ganglia of H. hermudensis and H. flori- 

 dana, the protoplasts of which are conspicuously different from 

 those of the ordinary cells in being denser, more homogeneous, 

 and more refringent. As is the case in H. actinophysa, the cells 

 of the subcortex of H. echinophysa are so gelatinous and translucent 

 that their form and relations can not well be ascertained without 

 resort to staining reagents, such as solutions of haematoxylin. 



Of the four species above described, specimens of three, Haly- 

 menia Gelinaria, H. pseudofloresia, and H. hermudensis, have 

 already been distributed in the Phycotheca Boreali-Americana of 

 Collins, Holden & Setchell, as indicated. This will, we trust, in a 

 measure atone for the lack of illustrations in the present paper. 



