NOSTOCEE. 243 
Size. Cells 004 mm. diam. Spores about ‘007 x :02-:03 
mm. 
Cylindrospermum leptospermum, Kutz. Tab. Phye. i., t. 99. 
f. 11, Bot. Leit. p. 198. 
In ditches and pools. 
“The confluent vegetative cells, with their obscure dissepiments, dis- 
tinguish this from every other British species.” —Ralfs. 
Of this also we have no personal knowledge. 
Plate XCIV. fig. 8. Portion of trichome with heterocyst and spores 
X about 400, After Ralfs, 
Spherozyga elastica. Ralfs Ann. Nat. Hist. 1850, 333, ¢. 8, fig. 9. 
Stratum deep bluish green, tender. 
Trichomes elongated, constricted at the dissepiments, joints 
about equal in length and breadth, but when dividing they 
lengthen, and though quadrate in the recent plant they acquire 
slightly rounded angles when dry. Heterocysts at first barrel- 
shaped, then elliptic. Spores cylindrical, 4-8 times longer 
than broad, ends at first truncate, but rounded after separation. 
Size. Cells about 005mm. Spores ‘008 x ‘025 mm. 
Spherozyga elastica, Agardh Icon. Alg. ? 
Cylindrospermum elongatum, Kutz. Tab. Phyc.i, t. 99,f. 
111. 
In bogs. 
“The moniliform filaments and shorter joints distinguish this species 
from S. leptosperma, and its elliptic heterocysts from S. Jacobi and S. 
Carmichaeli.”—Ralfs. 
Plate XCIV. fig. 7. Portions of trichomes with heterocysts and 
spores X about 400, after Ralfs. 
-GENUS 98, CYLINDROSPERMUM. (Kutz.) Ralfs 1850. 
Heterocysts terminal, single. Other characters the same as 
in Spherozyga. Spores originating in cells placed just below 
the heterocysts. 
Cylindrospermum macrospermum. Kutz. Tab, Phyc.1., t. 98, 
1 4A 
Trichomes curved or nearly straight, pale blue green, more 
or less interwoven ; joints globose or elliptic, often mixed with 
others somewhat cylindrical, either homogenous or granular. 
Heterocysts terminal, elliptical. Spores elliptic oblong, or 
oblong cylindrical, green or yellowish brown, darker brown 
when mature, granular, twice as long as broad. 
2M 
