28 CLEVE, VEGETABILISKT PLANKTON. 
Contributions to a deseription af the plankton- 
fiora of Sweden. 
Diatoms. 
Cheaetoceros balticus C1. N. sp. Chains multicellular, 
slightly silicious. Cellules in sagittal view quadrate, with 
slightly concave valvular margins. Foramina large, depres- 
sed hexagonal, smaller than the cellules. Cellules in trans- 
versal view nearly orbicular. Dimensions: long. ax. 0.01; sag. 
ax. 0.01; transv. ax. 0.008 mm. Awns delicate; terminal awns 
not decidedly stronger than the others, arising near the mar- 
gin of the valve, their basal part directed, obliquely outwards 
0.002 mm., their prolongations diverging in the transverse 
view at a right angle. — Endocysts lenticular, one valve 
being more convex than the other, covered with small pa- 
pille. Dimensions: long. ax. 0.006; sag. ax. 0.01; transv. ax. 
0,008 mm. Fig. 2. 
Brackish water: Bornholm (March 1896). 
This species has some resemblance to C. pelagicus CL. but 
I am for the present unable to identify them, as my descrip- 
tion of that form is insufficient, and I have no materials 
for a more complete examination. 
Chaetoceros commutatus C1. N. sp. Chains multicel- 
lular, delicate, straight. Foramina rounded quadrate, nearly 
as large as the cellules or larger. Cellules in sagittal view 
quadrate, with concave valvular margins; in transverse view 
broadly elliptical. Dimensions: long. ax. 0.012 (to 0,016); sag. 
ax. 0.012 (to 0.022); transv. ax. 0.008 mm. AÄAwns of the chain 
delicate, short, arising at the margin of the valve; their 
