ON THK DKSMIItlE.K OF NOUTH WALES. 17 



To this list of Dosmidiero found in North Wales must now be 

 added the two rare species, Cosinnritnit (ilobositni, Buhi. ; and Staunistnun 

 Saxonicuiit, Reiusch. 



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 "Rab. Fl. Eur. Alg.." nor yet to the figure given by 

 Nordstedt iu his " Desmidiese Arctoeaj, 1875." 



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

 them with the original specimens of Bulnheim, 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. 



Staiira^tntm 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 witli 

 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 globosuvi, Buln. 

 **Staura>itrum 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. 



Gosmarium Cambrieuin, nov. sp., (Plate V., Fig. 1.) 

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

 lateral, narrowed 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. 



Length, -046— -048 mm. ; breadth at the base, -036 — -038 mm. ; at 

 the end, •02— -022 mm. 



Allied to C. tetragonum and C. NijmanniaHum, from both of which it 

 differs in the character of the sides and ends and the number of 

 sinuations. 



Referexces to Plate V. 



Fig. 1. — Cosmarium Cambricitm. — Nov. sp. 

 „ 2.- — ,, coronatum. — Ditto. 



„ 3. — Staurastruni anatinum. — Ditto. 

 „ 4. — MicraMerias Aineiicana. forma major. — Reinsch. 

 „ 5. — Cosmarium cycUcum. — Lund. 

 „ 6. — ,, pseudonitidulum. — Nordst. 



„ 7. — Staurastruni megncanthum. — Lund. 



8. — „ Cerastes. — Lund. 



„ 9. — „ Arctiscon. — Ehr. 



„ 10.^ „ pseudofureigerum. — Reiusch 



