CLOSTERIUM. 367 



9. COSMARIUM QUADRATUM Ralfs. 



Plate LXXXVI. Figs. 11. and 12. 



Char. Fronds about twice as long as broad. Segments qua- 

 drate, in front view slightly compressed, smooth. 



Ralf&, 1. c. vol. xiv. t. 11. f. 8. ; Jenner, 1. c. p. 196. 



Hob. Rusthall Common, near Tunbridge Wells : Mr. 

 Jenner. Dolgelly : Mr. Ealfs. 



The front view of the segments is somewhat quadrangular, 

 the distal or free angles being slightly rounded, and the 

 proximate, protuberant. 



10. COSMARIUM CUCURBITA Breb. 

 Plate LXXXVI. Fig. 7. 



Char. Fronds small, about twice as long as broad, cylindrical, 

 with a slight constriction in the centre, minutely punctated. 

 End view circular. 



Ralfs, in Annals, vol. xiv. ; Jenner, in Flora of Tunbridge 

 Wells, p. 196. Cosmarium Cucurbita Desm., No. 1103. 



Hob. Dolgelly : Mr. Ralfs. Ashdown Forest and 

 Greatham bogs, near Pulborough : Mr. Jenner. 



This species approaches rather closely to Cosmarium cylin- 

 drum Ralfs, but the frond in that species is distinctly den- 

 tated, whereas in C. Cucurbita Breb. it is merely dotted : 

 it also has a great resemblance to Closterium cylindrus, but in 

 that plant the puncta are described as arranged in longitudinal 

 lines, whereas in Cosmarium Cucurbita they are scattered. 



59. CLOSTERIUM Nitzsch. 



Char. Fronds elongated, mostly crescentic, sometimes con- 

 jugating ; each formed of two similar segments, which 

 unite without constriction, and the free extremity of each 



