202 BRITISH DESMIDIA.CE.E. 



son's .-.perk's, although Wollo gives Brebisson's name as a 

 synonym. 



Docidium coronatum var. undulatum Hieronymus (Conj. in 



I'jiU'l. Pllan/enw. Ost-Afrik. 1S ( J."), p. ] 0) does not appear to 

 differ in any marked degree from an ordinary form of tin- 

 type. The measurements given by Schmidle (Ost-Afrika 

 Desmid. l,sl)<S, p. 2o) as "Uiam. 06/4; long. 180,./," must 

 refer to one semicell only, as is obviously shown by his 

 figure (t. i, f. 11). 



Turner (in the Naturalist, Oct. 1887, p. 290) records 

 Diiciiliii ni it<nlti/<t*iiiii var. l(il>i(il/ini, but we do not quite com- 

 prehend the distinguishing lent nres of this form. He suggests 

 that there is an apical incision, but does not definitely say so 

 (riilf. Naturalist., Sept. 1887, p. 275) ; neither do we know of 

 anything of the nature of an apical incision in any species of 

 this yenus. We recorded Turner's form, which was from 

 (iorniire, N. Yorks., in the ' Alga-flora of Yorkshire' (p. ."><)) 

 as r/<'/irnf;nii/(in curonnhnu var. iinilnlo^ntn- forma lab in to.-. 



2. Pleurotsenium eugeneum (Turn.) uol>. 



DwiiUmii eugeneum Turn. Fresh \v. Alg. E. India, 1893, p. '30, t. '3, f. 3 ; 

 Nurdst. Index Desm. 1890, p. 12(). 



Cells large, elongated and cylindrical, 10- IS times 



O ^ . 



longer than their diameter ; semicells with a prominent 

 basal inflation, lateral margins slightly sinuate, very 

 slightly attenuated towards the apex, which is rotnndo- 

 truncate and furnished with a ring of 20-24 pyrii'orm 

 tubercles (11 visible across the apex) ; cell-wall 

 smooth. 



Zygospore unknown. 



Length 070-720 /x; breadth at base of semicells 28- 

 '52 fj. ; breadth at apex 24 //,. 



< irmr. Distribution. India. 



The typical form does not occur in Britain. 



Turner's dimensions do not agree- with the si/A' and propor- 

 tion of his figure. The above measurements an- those given 

 by Turner in his text, but his figure measures: Length 712 /< ; 

 hn-adth nt base of semicells 45 n, at apex 31 fi. These are 

 much more in accordance with the proportions of the British 

 forms. 



