16 



R. Gronblad, New Desmids. 



E. spinulosum. 



1) Polar lobe considerably 



dilated at the end. 



2) Apex more retuse. 



3) The incision between polar 



and lateral lobes narrow 

 and acute. 



4) The incision between the 



upper and lower lateral 

 lobes acute or rounded. 



5) Cell-wall spinate. 



E. mononcylum. 



1) Polar lobe not at all or 



only very slightly dilated. 



2) Apex only slightly retuse- 



emarginate. 



3) The same incision widely 



open, rounded. 



4) The same incision widely 



rounded. 



5) Cell-wall spinate or gra- 



nulate. 



By a comparison of the figures above enumerated with 

 each other these differences seem to be of trifling import- 

 ance. But it is, as I should think, better to keep these 

 species separate than to unite them. — E. mononcylum is not 

 closely allied to E. gemmatum, to which it at first was referred 

 as a variety, the vertical view of them being very different, 

 and also the arrangement of the granules. 



Most of the forms and species which belong here are 

 tropical. A revision of the whole group would be very 

 necessary. 



Eu. verrucosum E h r. var. subplanctonicum, now var. 

 Robustius; lobo polari non dilatato; lobis lateralibus supe- 

 rioribus nullis vel ad minimum reductis, inferioribus latis. 

 Protuberantia centralis magna, elliptica; laterales autem 

 reductae. Membrana granulis permagnis armata. Long. 95, 

 lat. 85, crass. 53, isthm. 21 //. [N:o 997]. 



Hab. Domargard, Borga (S). PI. 3 fig. 29—30. 



Nearest to var. planctonicum West, Mngr. II pi. 40 

 f. 7 from which it is easily distinguished by the not dilated 

 polar lobe, the shorter and broader lateral lobes and the 

 much larger granules. 



Eu. spec. Only one semicell was seen. I therefore 

 do not describe it as a new species. Possibly it is a 



