SEBDENIA 165 
(S. Monardiana) and it is possible that the presence of such 
filaments may sometime be considered a character of sufficient 
importance to warrant a generic segregation. The whole matter 
of the affinities of the Sebdenia group appears to be in need of 
further study, especially in regard to the development of the cysto- 
carp. Schmitz and Hauptfleisch (Engler & Prantl, Nat. Pflanzen- 
fam. 17: 403. 1897) have placed the genus among the Rhody- 
meniaceae and have been followed in this by De-Toni (Syll. Alg. 
4: 530. 1900). It is to be remembered, however, that with J. 
Agardh the group was always a section or subgenus of Halymenia 
and that Berthold, who studied the development of the cystocarp, 
included it in the Cryptonemiaceae. Pending further studies, 
it is our impression that the genus should be kept close to Haly- 
menia. 
The scabrous appearance of parts of the thallus of Sebdenia 
heteronema might naturally suggest some affinity with Meristo- 
theca, but che tetraspores are decussately paired instead of zonate 
and the general vegetative structure is hardly congruent with 
that of Meristotheca. Тһе planc adheres rather imperfectly to 
paper when dried under pressure. It is decolorate and olive-green 
as it comes to us, preserved with formalin. Dr. Coker's no. 157 
was a synoptic one and it is not altogether certain to what his 
specific field notes under а, b, c, etc., may apply; under 157a, 
which probably means this, his note is "expanded Ulva-like 
thallus, dark red, almost purple.” 
PLATE 58. Sebdenia heteronema 
Photograph of the type specimen (Coker 157 р.р--пош liquid preservative), 
reduced to a little less than one third of the natural dimensions 
_ GRATELOUPIA Ag.* Sp. Alg. 1: 221. 1822 
The so-called species of this genus have been based chiefly 
upon the form of the thallus and the form is so notoriously variable 
ета С three species ies, of which 
the first two belong with the fater-proposed Chaetónglum, while the third, Grate- 
loupia filicina, has come down to us as the type of the genus Grateloupia, under the 
ағы principle. This mode of fixing a type is not sanctioned by the “American 
Сойе” of nomenclature, but, with the case poaae бөзі complicated by the existence 
of x: earlier and more or less uncertain Phor of Rafinesque, we are unwilling to 
venture any disturbance of the ыдым application of the generic name 
Grateloupia. | 
