BRITISH DESMIDIE-<E. 81 



Tab. XII. a. mature frond with endochrome ; b. empty frond ; c. mature 

 frond of small variety ; d. transverse ^-iew ; e. transverse view of small variety ; 

 f. end view ; g. sporangium. 



3. E. a-assum (Breb.) ; frond smooth ; segments three-lobed, sub- 

 quadrilateral ; terminal lobe cuneate, partly included in a notch 

 formed by the lateral lobes. 



Cosmarlum crassmn, Breb. in Meneyh. Sj/nop. Desm. p. 222. (1840). 

 Euasfnim Pelta, Ralfs, in Annals of Nat. Hist. v. 14. p. 190. t. 7. f. 1. (1844), 



(not Cosm. Pel fa, Corda, according to Breljisson) ; Trans. Bot. Soc. of 



Edin. p. 126. Hass. Br. Fi-eshtvater Algce, p. 380. 

 Euastrum crassum, Kiitz. Phycologia Germ. p. 135 (1845). 

 Euastrum (No. 5), Bailey, Amer. Bacil. t. 1. f. 26. 



/3. Smaller, sides more concave. 



Hab. Pools ; common. Dolgelley, Penzance, /. R. Weston Bogs near 

 Southampton ; Ashdown Forest, Sussex, and Fisher's Castle, Kent, Mr.Jenner. 

 Ambleside, "Westmoreland, Mr. Sidebotham. Aberdeen, Mr. P. Grant and 

 Dr. Dickie. Ben Muich Dhu and Glen Lin, Aberdeenshire, Dr. Dickie. 



/5. Dolgelley, /. R. 



Falaise, Brebisson. United States, Bailey. Germany, Kutzing. 



Frond comparatively large, visible to the naked eye, about three times 

 longer than broad ; of a quadrilateral form, with rounded ends ; terminal lobe 

 cuneate, partly included between the ends of the lateral lobes, rounded and 

 emarginate, the notch closed ; the segments of the frond are broad, three-lobed, 

 or rather each segment has a subquadrate base and a terminal lobe. The 

 basal portion is not attenuated, and each lateral margin has a broad shallow 

 sinus, in which there is frequently a slight intermediate rounded projection. 



The transverse view is two or three times longer than broad, with three 

 lobes on each side and one at each end. 



The empty frond is punctated. 



The var. /3, regarded by Brebisson as a distinct species, is smaller, the seg- 

 ments have more concave sides, their base is more inflated, and the angles 

 which include the terminal lobe are more elongated. 



The E. cornutum, Kiitz., diifers in having the outer angles of the lateral 

 lobes elongated into processes. 



Length of frond from ywz *° T5T ^^ ^"^ ^"^^^ 5 breadth from ^-^ to -^\^ ; 

 breadth of end lobe g-^. 



Tab. XI. fig. 3. a. frond with endochrome ; b. empty frond; c. transverse 

 \-iew ; d. end view ; e. frond of /3 ; /". end view. 



** Segments sinuated ; terminal lobe exserted and united with the 

 basal portion by a distinct neck, 



4. E.pinnatum, ; segments five-lobed ; end lobe exserted, dilated ; 



upper margin of lobes horizontal. 



Dolgellev, rare, J. R. 



