CODIUM. 331 
tinous expansion, with marginal lobes. This type naturally 
leads up to that of Codiwm bursa, Turn., where the thallus 
is globular, but fixed to the substratum by an extended 
base, the centre of the mass being filled with a loose net- 
work of filaments. The third series is represented by the 
species dealt with in the present Memoir, viz., Codiwm 
tomentosum, Stackh. In this series the thallus is cylin- 
drical and elongated, and branched more or less dichoto- 
mously. Finally, Agardh establishes a series based on 
the species Codiwm elongatum, C. Ag., where the branches 
are flabellate. 
The majority of the species of Codiwm are included in 
the third series, and these are by Agardh sub-divided 
again into two sections, dependent on the form of the 
lateral branches of the hyphe, which form the superficial 
palisade layer. These lateral branches, named “‘ utricles ”’ 
by Agardh, are, according to him, either (a) smooth and 
rounded at their apices, or (0) furnished with an apical 
umbo or point. Under the former Agardh includes C. 
tomentosum. A careful examination of the palisade layer 
of that species will show, however, that this distinction 
cannot be rigidly maintained, for some of the palisade pro- 
cesses are smooth, whilst others are distinctly mucronate 
fee Pl T., fig. 3). 
Enough has now been said to indicate the taxonomic 
position of the species under consideration, and to define 
its general relationship to other Chlorophycee. 
DISTRIBUTION. 
Codium tomentosum, the oldest known species of the 
genus, is widely distributed in the marine waters of the 
globe. If we accept Agardh’s view, the species is a native 
of the shores of the Atlantic Ocean. On the west it 
occurs especially on the shores of Florida and the Autilles, 
