COLLINS AND Howe: SPECIES OF HALYMENIA 177 
as are shown by a microscopic comparison of the vegetative 
characters of these two superficially similar plants. The cysto- 
carp of H. floridana, however, is commonly somewhat protuberant 
on both faces of the frond, while that of H. Gelinaria is commonly 
protuberant on only one face. In both, the spore-mass or “nu- 
cleus” is very dense, turbinate or oblate-spheroid, sometimes 
apparently two- or three-lobed, and is supported by a short stalk. 
In 1900 (Phyc. Bor-Am. 750) the senior author of the present 
paper used the name ‘“‘ Halymenia floridana forma dentata (Crouan) 
Collins” for a dentate-margined condition of the present species, 
citing Gelinaria dentata Crouan in Mazé & Schramm, Algues de 
Guadeloupe, as a synonym. In doing this he was, in effect, 
adopting the opinion (expressed in litt.) of a distinguished phy- 
cologist who was familiar with the Guadeloupe specimens dis- 
tributed by Mazé & Schramm but knew Halymenia floridana 
J. Ag. from description only. However, the Mazé, Alg. Guad. 
no. 1602, ‘‘Capesterre, Plage du bourg” in the herbarium of 
the British Museum, is certainly very different, as to species, at 
least, from either H. floridana or H. Gelinaria. Whatever may 
be the relation of other Guadeloupe specimens to these two 
species, the name dentata of Crouan, a ‘‘nomen seminudum”’ at 
best, can not, under the provisions of the ‘American Code” at 
least, be adopted for either, on account of the previously published 
Halymenia dentata Suhr. 
Halymenia Gelinaria adheres very firmly to paper when dried 
under pressure. 
Halymenia pseudofloresia sp. nov. 
Thallo violaceo-rubro, brevi-stipitata; stipite inferne subtereti, 
superne cuneato; fronde juvenili membranacea, gelatinosa, acetate 
ircumscriptione 
suborbiculari, ovata, cuneato-obovata, vel nonnunquam va de 
irregulari, Jongitudine 7-30 cm., pro 
tionibus stipitatis munita; rachidibus 1-8 cm. latis, lobis et pro- 
lificationibus plerumque lanceolatis, serratis vel seriebus loborum 
etc. secundariorum munitis; superficie haud nitente, plerumque 
plana, sed aetate provecta minute verruculosa; medulla frondis 
laxa, subvacua, filamentis sparsis percursa, filamentis trans- 
versalibus crebris, filamentis stellatis paucis, inconspiculs; 
subcorticali indistincte filamentoso, cellulis 20-50 » diam.; strato 
