172 Collins and Howe: Species of Halymenia 



less developed conditions these radiating arms seem to lose them- 

 selves among the ordinary filaments of the medulla, but in older 

 well-developed states some of these radiating arms may be traced 

 directly to other ganglia, which thus form an interconnecting 

 system. When a portion of the thallus is crushed on a glass slide 

 and the other parts are reduced to a confused mass these ganglia 

 and their rays often persist with little change. Septa in these 

 enlarged specialized filaments are distant and irregularly placed. 

 We have seen but few tetraspores and these were apparently not 

 very well developed. Cystocarps have not been observed, al- 

 though hundreds of specimens have been examined with the hope 

 of finding them. In one lot of material, however, from Grasmere, 

 we found small red spots resembling cystocarps under a hand lens, 

 but these spots were apparently caused by the irritation of some 

 endophyte or through Injury by some small animal. 



Halymenia bermudensis evidently finds its nearest ally in the 

 little-known H. floridana J. Ag.,* with the type of which, as also 

 with the Peruvian Sebdenia heteronema M. A. Howe,t it shows 

 more or less agreement in having usually rather conspicuous sub- 

 stellate medullary ganglia. It differs, however, from H. floridana, 

 which is now known only from southern Florida and from near 

 Beaufort, North Carolina {W. D. Hoyt), in its darker color (roso- 

 lane purple rather than pinkish vinaceous), in its commonly more 

 lobed or dissected thallus, in its rather firmer texture, in its thicker, 

 firmer, and less monostromatic cortex, and in its possible loss of 

 sexual reproduction. Although, in a general way, the two species 

 show a similarity in the medullary ganglia and the dimorphous 

 medullary filaments, a critical comparison shows certain points 

 of difference in these organs. The ganglia are less numerous, 

 less conspicuous, and less obviously anastomosing in H. bermu- 

 densis. The arms on leaving the ganglion commonly taper away 

 gradually, usually without a septum or obvious interruption of the 

 protoplast; in H. floridana, the arms usually taper towards the 

 ganglion and usually have a septum or a wide interruption of the 

 protoplast near the place of emergence. As a result of these 



* Anal. Alg. 59. 1892. Howe, Bull. Torrey Club 38: SH- 1911; Mem. Torrey 

 Club 15: 164. 1914- 

 t Loc. cit. 



