SPIROT^NTA. 45 



SCOTLAND. Ross, Inverness, Aberdeen, Kincardine, 

 Perth, Stirling; zygospores from ( 1 ammie, Kincardine 

 (Roy $ Ji isse it ) . Sutherland ! 



I UKLAXD. Dublin and Wicklow (. I /rA'v). Near Locli 

 Brin, Gralway! 



(ri'iHji-. Distribution. France. Germany. Switzer- 

 land. Austria. Hungary. Italy. Norway. Sweden. 

 Holland. Spitzbergen. Nova Zembla. Tinted Slates. 



11. Spirotaenia bispiralis West. 

 (PI. Ill, fig. 13.) 



Spirotsenia Uspiralis West, Alg. W. Ireland, 1892, p. 133, t. 20, f. 8; 

 Liitkem. Gatt. Spirotacn. 1895, p. 57 ; Nordst. Index Desmid. 1896, 

 p. 02. 



Cells large, 5 times longer than their diameter, fusi- 

 form, poles subtruncate ; chloroplast axile, with two 

 narrow ridges arranged in close spirals making about 

 9 revolutions. 



Zygospore unknown. 



Length 86-1 00 /i ; breadth 18-20/u; breadth just 

 below apices 4-6 /n. 



IRELAND. Near Westport, Mayo ! 



This plant lias only once been observed, but if its characters 

 are constant it is a well-marked species. If the number of 

 spiral ridges is variable it is probably only a form of 8. nlixnirti 

 Ralfs. 



12. Spirotsenia trabeculata A. Br. 



(PI. V, fig. 6.) 



Spirotsenia trabeculata A. Br. in Eabenh. Alg. 1856, no. 543 ; Do Bary, 

 Conj. 1858, p. 75; Eabenh. Krypt. Fl. Sachs. 1803, p. 178; Lutkem. 

 Gatt. Spirotam. 1895, p. 5, 95, t. 1, f . 20 ; Nordst. Index Desmid. 1896, 

 p. 256 ; West & G. S. West, Alg. N. Ireland, 1902, p. 19. 



Cells of medium size, 5-7-^ times longer than their 

 diameter, subcylindrical, gradually attenuated from the 

 middle towards the apices, which are subtruncate ; 

 chloroplast axile, scarcely reaching the extremities of 

 the cell, cristate, with 5 or (3 slightly spiral ridges 



