137 
Vs of the length of the cell. Chromatophore 
1, in front, large ivith turned lobes. Awns 
straight, stijf, very long, issuing from the 
angles of the cell, Crossing one another at 
the insertion; two of them proceed in a sa- 
gittal direction, two diverging from the first 
at acute angles; terminal awns diver ging, in 
a front view, at a largely obtuse angle. 
Spores unknown. 
Beslægtet med C. bottnicum og C. cas- 
picum, men adskilt ved de stærkt diverge¬ 
rende Terminalhorn. 
Fig. 7. Chætoceras 
rigidum Ostf. 
a. Kæde i Frontstilling; 
b. Sidestilling. ( 300 /i). 
11. C. simplex n. sp. 
Cells solitary or two together, in a front view rectangular , 
wider than long (12—16 p long, 16 — 24p wide), in a side view 
elliptic. Valves concave with a slight convexity in the middle. 
Chromatophore 1, situated 
close to the one valve. Awns 
delicate, very long, issuing 
from the angles or a little 
within the angles, then tur- 
ning sharply off, all in sa- 
gittal direction; often the 
two awns to the same side 
cross one another at the basal thirdpart; in a side view the awns 
are nearly parallel. Spores unknown. 
Beslægtet med de to andre enlige Arter, C. gracile Schtitt og 
C. septentrionale Oestr., men adskilt ved den ene Kromatofor og 
Hornenes Forløb. 
12. Coscinodiscus radiatus Ehbg., s. 1. 
13. Melosira Borreri Grev., var. subglobosa Grunow, 1. c. 
p. 128, PI. 4, f. 13. 
Fig. 8. Chætoceras simplex Ostf. 
a. Celle i Sidestilling; b, c. Frontstilling. 
( 300 /i). 
