60 SEAWEEDS 
but of equal size and susceptibility to conjugation 
during motility. 
This small order is of limited geographical range. 
Zanardinia collaris, the only species of the genus, 
occurs in the warm Atlantic (Europe and America) 
and in the Mediterranean, while the few species of 
Cutlerta have a wider range north and south, C. 
multifida being a native of the North Atlantic as 
far north as Britain and Scandinavia. 
’ 
DIcTYOTACE. 
General Characters—The Dictyotacew resemble the 
Cutleriacee in the non-conceptacular nature of the 
reproductive organs, and in these being of three 
sorts—female, male, and non-sexual. Paraphyses 
occur on the thallus, though not directly in asso- 
ciation with the reproductive organs. While all the 
reproductive bodies of the Cutlertacce: are ciliated, 
those of the Dictyotaceew are all unciliated. No ob- 
servation of fertilisation has been made in the case 
of the bodies presumed to be male and female, and 
this character is ascribed to them on comparative 
grounds. The growth of the thallus, which in 
general habit resembles that of the Cutleriacea, is not 
trichothallic, but by an apical cell (Dictyota) and by 
groups of equivalent meristematic cells in tha other 
genera, although in their earlier stages Taonia and 
Dictyopteris at least have, hke Dictyota, an apical 
cell. 
The Thallus of Dictyota, Zonaria, Taonia, 
