1922] TAYLOR—PHAEOPHYCEAE 439 
Order CycLosporaLEs.—Plants of this order are strictly 
oogamous. 
Suborder DicryoTINEAE.—Morphological alternation of similar 
generations present. 
Family Dictyotaceae—Characters of the suborder. The game- 
tangia are aggregated into definite areas or sori, and the asexual 
reproduction is by tetrasporangia, motile zoospores being replaced 
by four non-motile elements. The life cycle of Dictyota is fully 
known. Cultural studies showing the course of the development 
have been made by Hovyr (3), and cytological studies by Mottrer 
(13) and Wrtu1aMs (35, 36), showing reduction in tetraspore 
formation. 
Suborder LAMINARINEAE.—Morphological alternation of dis- 
similar generations present, gametophyte smaller than the sporo- 
phyte. 
Family Laminariaceae.—Characters of the suborder. Members 
of this family are almost all large plants. Reproduction was 
thought to be strictly by zoospores until SauvacEau showed that 
the zoospores produced a microscopic gametophyte. The results 
of the various studies have previously been described. 
Suborder Fuctnear.—Only cytological alternation of genera- 
tions present. 
Family Fucaceae——Characters of the suborder. This family 
forms the spores within pits or conceptacles. Still inclosed, the 
spores undergo a few cell divisions, or even only a few nuclear divi- 
sions, forming the gametes which are then shed as egg and sperm. 
Cytological studies have been made by several workers, including 
YAMANOUCHI (39), confirming the morphological and cultural obser- 
vations. This is the climax family of the brown algae, and repre- 
sents the greatest reduction of the gametophyte possible while 
still retaining an alternation. 
The writer wishes to express his indebtedness for many helpful 
suggestions to Professor I. F. Lewis, of the University of Virginia. 
Marine Brotocicat LABORATORY 
AND THE 
UNIVERSITY OF PENNSYLVANIA 
