94 BRITISH DESMIDIE^. 



worth near Petworth, Sussex ; Hampshire, &c., Mr. Jenner. Hill of Rhoil 

 (alt. 1600 feet), Glen Derry, Aberdeenshire, Dr. Dickie. Near Aberdeen, Mr. 

 P. Grant. 



Falaise, Brebisson. 



Frond large, disciform, quite smooth, deeply constricted at the middle, the 

 constriction forming a linear notch on each side. The segments are semi- 

 orbicular, quite entire, and not punctate. 



The endochrome is usually somewhat radiate, and the vesicles are small. 



The transverse view is elliptico-lanceolate or fusiform. 



This species I formerly considered to be the Euastrum integerrimum^ Ehr., 

 but M. De Breliisson has convinced me of my mistake. It is a larger plant 

 than that figured by Ehrenberg, and more perfectly orbicular. It diifers from 

 C. Cucumis by its larger size and disciform appearance. 



Length of frond from g^r ^^ tIt '^^ ^^ ^^^^ '■> breadth from ^^r to glr > 

 breadth at constriction from ytso ^^ ttts- 



Tab. XV. fig. 3. a. frond with endochrome ; b. transverse view. 



4. C. pyramidatum (Breb.) ; frond oval with flattened ends, deeply 

 constricted in the middle ; segments punctate, entire. 



Cosmarium ovale, Ralfs, in Annals of Nat. Hist. v. 14. p. 394 (in part), t. 11. 



f. 7. a, b, c. (1844) ; Trans. ofBot. Soc. of Editiburgh, v. 2. p. 150 (in 



part) ; Jenner, Flora of Tunbridge Wells, p. 196, 

 Cosmarium pyramidatum, Brebisson in lit. (cum icone) (1846). 



Probably common. Dolgelley and Penzance, J. R. Barmouth, Rev. T. 

 Salwey. Near Tunbridge Wells ; Midhurst ; Henfield, &c., Sussex ; Reigate, 

 Surrey, Mr. Jenner. Near Congleton, Cheshire, and near Ambleside, West- 

 moreland, Mr. Sidebotham. Kerry, Mr. Andreios. Hill of Rhoil (alt. 1 600 

 feet). Dr. Dickie. Near Aberdeen, Mr. P. Gra?it. Near Manchester, 3Ir. 

 Williamson. 



Falaise, Brebisson. 



Frond about twice as long as broad, varying much in size, subelliptic, with 

 flattened ends, deeply constricted at the middle, the constriction forming a 

 linear notch on each side. 



The empty frond is pimctate and entire at the margin. Transverse view 

 broadly elliptic. 



The sporangia which I have occasionally met with at Dolgelley are orbicular 

 and tuberculated. 



From Cosmariutn Cucumis and C. Ralfsii this species may be known by its 

 puncta and depressed ends. From C. ovule, with which I formerly united it, 

 it differs in its entire margin and truncated ends. In form the segments ap- 

 proach those of C. Botrytis, but are not granidate. 



Length of frond from ^^r ^^ 2-5T ^^ ^^^ "^^^^ ^ breadth from yj-g to -jI^ ; 

 breadth at constriction from -^-kt to tAo- 



Tab. XV. fig. 4. a, d. fronds with endochrome ; b. empty frond ; c, e. lateral 

 views ; /. transverse view. 



