86 BRITISH UESMIDIE.E. 



a. High Beech, Essex, Hassall. Near Aberdeen, Mr. P. Grant. 

 (3. Dolgellejs /. R. Ambleside, Westmoreland, Mr. Sidehotham. "Weston 

 Bogs near Southampton, Mr. Jenner. 



y. Ambleside, "Westmoreland, Mr. Sidehotham. 



Z. Falaise, Brebisson. 



As I have seen no authentic specimens, and am not sure whether the number 

 and position of the inflated protuberances are constant, I may have united 

 under this name more than one species. The variety y. especially differs from 

 the other forms in the number and arrangement of the tubercles, but as I have 

 seen no specimen of it, and Mr. Jenner only one or two fronds mixed with 

 other Desmidiese, which Mr. Sidehotham forwarded from Westmoreland, I 

 have no means of deciding where it should be placed. At the same time I am 

 unwilling to omit so interesting a form, and as it agrees in outline with the 

 variety /3, I have placed it here, in the hope it may be recognized. 



I have gathered near Penzance a single frond, which I suppose may be the 

 state figured by Mr. Hassall. The protuberances were distinct on one seg- 

 ment, but not on the other. In form it resembled E. ansatum ; the inflations 

 on the front surface were its most obvious distinction from that plant ; in a 

 transverse view I presume it would resemble the other varieties. 



The variety /3. is not uncommon near Dolgelley ; the segments are emarginate 

 at their sides and the end lobe is slightly dilated. On the front surface are 

 five protuberances, but their arrangement is different from that in Mr. Hassall' s 

 figure ; they are also less distinct and sometimes scarcely perceptible. An 

 Euastrum, however, gathered at Falaise, for the sight of which I am indebted 

 to Dr. Dickie, unites the /5. form with protuberances exactly like those repre- 

 sented by Mr. Hassall. 



This variety agrees in some respects with Euastrum pectinatum and E. gem- 

 matnm, but has a terminal linear notch, and the end view exhibits two nearly 

 quadrate and slightly notched lobes. 



Length of frond of var. /3. -g-i-g- of an inch ; breadth at base -g\^ ; breadth of 

 neck ^g'gg ; breadth at end y^g-g . 



Length of frond of Falaise specimen -^-^ of an inch ; breadth at base j-j-g ; 

 breadth of neck ^aVz ? hreadth at end yyVg • 



Tab. Xin. fig. 5. a. frond of /3. with endochrome ; b. empty frond; 

 d. transverse view ; e. empty frond of y. 



Tab. XI"V. fig. 3. a. frond as figured by Hassall in Brit. Alg. ; b. frond of 

 the Falaise variety ; c. end view. 



12. E. pectinatum (^Y^h.) ; segments three-lobed;terminallobe dilated, 

 scarcely emarginate ; lateral lobes horizontal, emarginate ; end view 

 two-Iobed at each end and two lobules on each side. 



/3. terminal lobe emarginate at each side. 



Cosmarium pectinatum, Breb. in Menegh. Synop. Desmid. in Linncea 1840 



p. 222. 

 Euastrum gemma turn, ^nXh, Annals of Nat. Hist. vol. 14. p. 191. t. /. f. 4. 



