ox the desmible.e of north wales. 73 



ON THE DESMIDLE.E OF NORTH WALES. 



( Continued from page 43.) 



To the list of Desmidieae found in North Wales, which was 

 published in the February number of this journal, must now be added 

 the two rare species, Cosmarium globosum, Bum. ; and Staurastrum 

 Saxonicum, Reinsch. 



At the time when that list was prepared, there was some doubt as 

 to the identity of my specimens with the former plant, inasmuch as 

 they do not correspond in certain particulars to the description 

 published in "Bab. Fl. Eur. Alg.," nor yet to the figure given by 

 Nordstedt in his " Desmidieae Arctoeae, 1875." 



The kindness of Dr. M. C. Cooke has now enabled me to compare 

 them with the original specimens of Bnlnheim, published in " Raben- 

 horst's Alg. Exsic," and I conclude that the species is subject to 

 considerable variation, and that there is nothing in the form taken by 

 myself in Wales to entitle it to rank as a distinct species. 



Staurastrum Saxonicum has been twice figured by Reinsch, and 

 between his two drawings there are material differences. My plant 

 combines the characters of the two, and as I cannot identify it with 

 any other known species, I conclude that it must really be referred to 

 this rare form. 



As neither of these plants has been hitherto detected in the British 

 Isles, they must be added to our list as — 



** Cosmarium globosum, Bum. 

 **Staurastrum Saxonicum, Reinsch. 



There remain to be noticed three entirely new species, and as Dr. 

 Cooke has already dealt with these in the last number of " Grevillea," 

 I borrow, with his permission, the descriptions which he has given, 

 adding figures drawn from my own specimens. 



Cosmarium Cambricum, nov. sp., (Plate V., Fig. 1.) 



Frond longer than broad ; constriction, linear ; segments, quadri- 

 lateral, naiTowed from the base upward ; sides, with two sinuations, 

 and one in the centre of the end, the latter rather the broadest ; side 

 view, segments oval, narrow, rounded at the ends, with a shallow 

 constriction ; end view, elliptical. 



References to Plate V. 



1. — Cosmarium Cambricum. — Nov. sp. 

 2. — „ coronatum. — Ditto. 



3. — Staurastrum anatinum. — Ditto. 

 4. — Micrasterias Americana, forum major. — Reinsch. 

 5. — Cosmarium cyclicwm. — Lund. 

 G. — „ pseudanitidulMm. — Xordst. 



7.— Staurastrum megacanthum. — Lund. 

 8. — ,, Cerastes. — Lund. 



9. — „ Arctiscon. — Ehr. 



10. — „ lofurcigerum. — Reinsch 



