1 9 I 
Classification of Green A Igce. 
n. Oocardinm. Nageli, 1849 . 
Adhering to the surface of rocks and forming a 
calcareous incrustation composed of a number of 
parallel vertical tubes, the free end of each of which 
is inhabited by an individual cell. 
Cells ovoid, equatorial constriction slight, parallel 
to the axis of the tube. Chromatophores two, 
one in each semicell, each composed of a central body 
containing a pyrenoid and of radiating plates; 
narrowed towards the lower end so that the cell is not 
symmetrical about the plane perpendicular to the axis 
of the tube, the lower part of the cell containing the 
nucleus and the narrowed ends of the chromatophores. 
12 . Tetmemorus. Ralfs, 1845 . 
Cells cylindrical or spindle-shaped, with an aquatorial 
constriction and a narrow furrow at e 2 ich end. 
Chromatophore axile with a single row of pyrenoids. 
13 . Eucistrim. Ehienberg, 1831 . 
Cells elongated or broadly elliptical, somewhat 
flattened, and with a deep equatorial constriction. 
Outline of ihe cell with symmetrical rounded lobes and 
a well marked furrow at each end Chromatophore 
axile composed of longitudinal rad'ating plates. 
14 . Micvasterias. Agardh, 1827 . 
Cells straight, circular or broadly elliptical, flattened. 
Each semicell three-lobed, the terminal lobe entire or 
bayed, the laterals symmetrically furrowed or cut. 
Chromatophore an axile plate in the plane of the cell, 
sometimes with subordinate plates, as in Euastrum. 
15 . / Irthrodesmus . Ehrenberg, 1836 . 
Like Cosmarium, but with two or four long processes 
arising from the wall of each semicell. 
16 . Holaccinthum. Lundell, 1871 . 
Cells oval or nearly round, sometimes angular, 
with a deep equatorial furrow and two rows of long 
hornlike unbranched processes on the edges and a 
swelling on each side of the semicell. Chromato¬ 
phores parietal, platelike, each with a pyrenoid, four 
or six in each semicell. 
17 . Schizacanthum. Lundell, 1871 . 
Like Holacanthum, but marginal processes branched. 
Several pyrenoids in each chromatophore. 
18 . St aura strum. Meyen, 1829 . 
Cells oval, with a deep equatorial furrow. In end view, 
usually triangular, quadrangular or polygonal, often 
