106 BRITISH DESMIDIEJE. 



tt Frond smooth. 



24. C. Phaseolus (Breb.) ; segments smooth, reniform ; constriction 

 forming a linear notch on each side ; end view eUiptic with a sUght 

 projection at the middle of each side. 



Cosmarium Phaseolus, Brebisson, in Menegh. Synop. Desmid. in Linncea 

 1840, p. 220. Brebisson, in lit. cum icone. 



Dolgelley and Penzance, /. R. 



Falaise, Brebisson. 



Frond larger than that of Cosmarium bioculatum, deeply constricted at the 

 middle, the constriction forming a linear notch on each side ; segments twice 

 as broad as long, reniform, quite smooth and entire. The end ^iew is elliptic 

 and shows on each side a shght conical inflation, resembling that seen in 

 Xan th idium fascicu la turn . 



The small circular mflation which is present at the centre of each segment 

 compels me to associate this with the other inflated species ; but it differs 

 from all of them in its smooth fronds, and the slight inflation can he detected 

 only by an end view. Cosmarium Phaseolus is far more likely to be mistaken 

 for C. hioculatum, and indeed is placed next it by Brebisson ; but it is larger, 

 its segments are reniform, not elliptic, and the notches caused by the con- 

 striction are not gaping as in that species. 



Length of frond y|^ of an inch ; breadth -g-i^ ; breadth at constriction x^jg-. 



Tab. XXXII. fig. 5. a. front \dew ; h. empty frond; c. end view. 



*** Constriction not forming linear notches at the sides ; end view 



circular. 

 t Frond rough with pearly granules which give a denticulate appear- 

 ance to the outline. 



25. C. cylindi'icum (Ralfs) ; segments granulated, subquadrate in the 

 front view, broadest at the extremity ; end view circular. 



Cosmarium cylindricum, Ralfs, Annals of Nat. Hist. v. 14. p. 392. t. 11. 

 f 1 (1844) ; Trans, of Bot. Soc. of Edinhurgh, v. 2. p. 148. t. 16. 

 Jenner, Fl. of Tunbridge Wells, Supplement, p. 18. Hass. Br. Alg. 

 p. 365. 



Wet sides of a cave at Lamorna Cove near Penzance, and wet sides of a 

 cliff at Machynlleth, North "Wales, J. R. Ashdown Forest ; near Tmibridge 

 Wells, and near Battle, Mr. Jenner. 



Frond minute, cylindrical, about twice as long as broad. The subquadrate 

 segments are broadest at the extremity, which is truncate, somewhat tapering 

 towards the junction, and rough with pearly granules which give a dentate 

 appearance to the outline. 



Cosmarium cylindricum may be known from C. Cucurbita by the condition 

 of its segments described above. 



Length of frond -^\-g of an inch ; greatest breadth yoVo '■> hreadth at con- 

 striction Y^^. 



Tab. XVII. fig. 4. «. mature frond; b. empty frond ; c. end view. 



