NOSTOCE.E. 243 



SIZE. Cells -004 mm. diam. Spores about -007 x -02--03 

 mm. 



Cylindrospermum leptospennum, Kutz. Tab. Phyc. i., t. 99. 

 f. 11. Bot. Leit. p. 198. 



In ditclies and pools. 



" The confluent vegetative cells, with their obscure dissepiments, dis- 

 tinguish this from every other British species." Rolfs. 

 Of this also we have no personal knowledge. 



Plate J.QIV. fig. 8. Portion of trichome with heterocyst and spores 

 X about 400. After Ralfs. 



Sphaerozyga elastica. Ralfs Ann. Nat. Hist. 1850, 333, t. 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 -005 mm. Spores -008 x '025 mm. 



Sphcerozyga 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 Sphcerozyga. Spores originating in cells placed just below 

 the heterocysts. 



Cylindrospermum macrospeimum. Kutz. Tab. Phyc. I., t. 98, 



f- * 



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. 



2 M 



