438 BOTANICAL GAZETTE [DECEMBER 
Family 7. Stilophoraceae.—Reproductive organs lateral on 
special branched supports, thallus erect on the substratum. As 
understood here, this family includes KJELLMAN’s Stilophoraceae, 
Spermatochnaceae, and Sporochnaceae. The sporangia are borne 
on branched filaments developed from superficial cells of the thallus, 
and both sporangia and gametangia are known. Parts of the life 
cycle have been traced by KyYLIn (10). 
Family 8. Ralfsiaceae.—Reproductive organs at least in part 
lateral on special branched supports, thallus incrustating. Here 
we may include with the Ralfsiaceae also KJELLMAN’s Lithoderma- 
taceae. In both the gametangia are borne laterally on special 
branched filaments arising from the surface, but the sporangia are 
only so borne in the Ralfsiaceae, in Lithoderma being but modified 
surface cells. The life history is unknown from the experimental 
viewpoint. 
Suborder DicryostpHONINEAE.—Morphological alternation of 
dissimilar generations present or inferred, the sporophyte exceeding 
the gametophyte in size. 
Family Dictyosiphonaceae-—Characters of the suborder. The 
forms are branching, have an apical cell, and differentiate axial and 
cortical areas. The life history, worked out by SAUVAGEAU (31), 
has previously been described. This is a very important group, 
as it indicates an intermediate step in the development of a micro- 
scopic oogamous thallus, such as is shown in Laminaria. 
Suborder CUTLERINEAE.—Morphological alternation of similar 
or of dissimilar generations present, gametophyte when different 
larger than the sporophyte; growth trichothallic. 
Family Cutleriaceae-—Characters of the suborder. The life 
history of this group is well known, thanks to the cultural studies 
of SAUVAGEAU, CHURCH, and several others, and to the cytological 
studies of YAMANOUCHI on Cuilleria (40, 41) and Zanardinia (42). 
The alternation shown by the cultural studies has been shown to 
be associated with a haploid and diploid nuclear constitution, reduc- 
tion taking place in the sporangia. In Zanardinia the two genera- 
tions are essentially alike, but in Cwéleria the reduced and flattened 
sporophyte was long known as Aglaozonia, and thought to be an 
entirely different genus. 
