170 SEAWEEDS 
established on insufficient grounds. Urospora and 
Gomontia have as yet been recorded only in Europe, 
but the latter has probably a much wider area. All 
the genera are represented in British seas. 
ULOTRICHACE. 
General Characters—The genera here brought 
together are usually classified as follows: Ulothria 
under Ulotrichacew, and Chatophora, Bolbocoleon, 
Entoderma, Epicladia, Pheeophila, <Acrochete, and 
Acroblaste under Chetophoracee. The limits between 
these two orders are, however, hard to define, and 
they do not appear to rest on very weighty characters. 
Both are much more largely represented in fresh- 
waters with numerous generic types not occurring in 
the sea, and a discussion of the propriety of treating 
these orders as one or separately is out of place here. 
There is certainly no strong reason for separating by 
ordinal division the genera dealt with here. The 
thallus is a simple branched or unbranched cell-row, 
with one nucleus in each cell, and the reproduction 
is by the conjugation of equal gametes with two 
cilia, and non-sexually by zoospores with two or four 
cilia. Vegetative forms of propagation are also 
known. 
The Thallus—In Ulothrix the thallus consists 
ordinarily of a single cell-row, attached at the base 
by a holdfast. The cells are all equally capable of 
division, except the basal one, which is generally 
more elongate than the others. Chetophora is very 
