90 
Blackman and Tansley. 
8 , liaphidium. Kiitzing, 1845. 
Cells acicular or fusiform, curved or straight, with 
pointed or rounded ends; usually free hue sometimes 
united in indefinite colonies. Pyrenoid usually absent. 
9. Coccomyxa. Schmidle, 1901. 
Cells oval, often slightly curved, sometimes with narrowed 
ends, isolated, or in pairs or fours, embedded in 
mucilage. Chloroplast parietal without a pyrenoid. 
Reproduction by vegetative division into two or four. 
[This appears to be a genus closely allied to Raphidiutn and 
Dactylococcus, but adapted to aerial life.] 
Series B. Cells crescentic, embedded in thin mucilage. 
\ 
10. Nephrocytium. Nageli, 1849. 
Cells reniform, occuring in ovoid groups of 2-16, the 
individual cells separated from one another l>y 
mucilage and the whole group surrounded by the 
distended mother-cell-wall, which retains a sharp 
contour. 
11. Kirchneriella . Schmidle, 1893. 
Cells semilunar or vermiform, occurring as a cluster 
within a mucilaginous investment, which soon becomes 
diffuse. 
t 2. Selenoderma. Bohlin, 1897. 
Cells semilunar, more or less widely scattered in a flat 
indefinite mucilaginous matrix. 
Series C. Cells crescentic to spherical, united to form a ccenobium 
radially symmetrical in three dimensions. 
13. Selenastrum. Reinsch, 1867. 
Ccenobium of 4-16 crescentic cells, cohering by their 
convex surfaces to form an approximately centric 
group. 
14. Sorastrum. Kiitzing, 1845. 
Ccenobium centric, the cells being united at the centre 
by short stalks. Cells rounded to crescentic, with 
short spines exteriorly. 
15. Coelastrum. Nageli, 1849. 
Ccenobium a hollow sphere, unually wdth intercellular 
gaps, composed of few or many cells which are 
spherical or polygonal. The cells are known to live 
singly in media rich in oxygen. 
Series D. Cells round to crescentic, united to form a uniscriate 
colontj or ccenobium. 
