DIVISION INTO GROUPS OR SERIES. 
For purposes of classification the Alg® may be conveniently grouped under 
three principal heads or sub-classes, which are, for the most part, readily distin- 
guishable by the colour of the frond. They are named and defined as follows, viz. 
1. Melanospermeoe. Plants of an olive-green or olive-brown colour. Fructifica- 
tion monoecious or dioecious. Spores olive-coloured, either external, or con- 
tained, singly, or in groups, in proper conceptacles ; each spore enveloped 
in a pellucid skin ( perispore ), simple, or finally separating into two, four, or 
eight sporules. Antlieridia , or transparent cells filled with orange-coloured, 
vivacious corpuscles, moving by means of vibratile cilia. Marine. 
2. RHODOSPERMEiE. Plants rosy-red or purple, rarely brown-red, or greenish-red. 
Fructification of two kinds, dicecious : — 1, Spores ( gemmules , Ag.) contained 
either in external or immersed conceptacles, or densely aggregated together 
and dispersed in masses throughout the substance of the frond : 2, Spores , 
commonly called tetraspores ( gemmules , Thw.), red or purple, either external 
or immersed in the frond, rarely contained in proper conceptacles ; each spore 
enveloped in a pellucid skin ( perispore ), and at maturity separating into four 
sporules. Antlieridia (not observed in all) filled with yellow corpuscles. 
Marine , with one or two exceptions. 
3. Chlorospermeje. Plants grass-green, rarely a livid purple. Fructification dis- 
persed through all parts of the frond ; every cell being capable of having its 
contents converted into spores. Spores ( Spioridia , Ag.) green or purple, 
formed within the cells, often (always ?) at maturity vivacious, moving by 
means of vibratile cilia. Gemmules ( Coniocystce , Ag.) or external vesicular 
cells, containing a dense, dark-coloured, granular mass, and finally separating 
from the frond. Marine , or, more frequently , living in fresh-water streams , ponds , 
and ditches , or in damp situations. 
