2 4 O Blackman and Tans ley. . 
the forms included by Bohlin under this name has led us to the con¬ 
clusion that they are too remote from the four classes just considered 
to be dealt with here, and that their real affinities are probably with 
quite other groups of Algae. 
ADDENDA. 
"ITERY soon after commencing the publication of this system of 
V classification, we decided that it would be more convenient to 
include diagnoses of all sufficiently known genera, and not, as 
indicated in the Introduction, of the more important ones only. This 
scheme has been carried out thence-forward to the best of our know¬ 
ledge ; though no doubt a few adequately known genera have been 
overlooked. The following omissions have been noticed during the 
progress of the work. 
Brachiomonas. Bohlin, 1897 . To follow Chlamydomonas , p. 23 . 
Body pointed behind and produced into four lateral 
processes anteriorly. First vegetative division longi¬ 
tudinal. Planogametes of the same form as the 
vegetative cells, but of varying sizes and tending to 
conjugate anisogamously. 
Chroolcpus. Kaisten, not Agardh, 1891 . To follow Trentepohlia , 
p. 166 . 
Thallus consisting of an epiphytic irregular disc, one 
cell thick, which produces also upright free branches 
of some length (resembling Trentepohlia.) Zoo¬ 
sporangia may be formed on either the disc or the 
upright branches. 
Dictyocystis. Lagerheim, 1890 . To follow Dictyosphaerium, p. 71 . 
Like Dictyosphaerium , butchromatophore radiating from 
a central pyrenoid. 
Elakatothrix. Wille, 1895 . To follow Actinastruni , p. 91 . 
Cells spindle-shaped, arranged in a longitudinal series, 
and surrounded by a mucilaginous sheath. Chroma- 
tophore parietal containing a large pyrenoid and 
covering the whole cell-wall except at the ends. Cell- 
division only in the transverse direction. 
Ichthyoccrcus. West and G. S. West, 1897 . To follow Tetmemorus> 
p. 191 . 
Like Tetmemorus, but terminal furrows broad and 
shallow, and a short spine on each of the four angles 
of the cell. 
Lauterhorniella. Schmidle, 1900 . To follow Crucigenia , p. 91 . 
Cells united by mucilage to form four-celled ccenobia; 
seen from the edge of the coenobium each cell is semi- 
