CLOSTERIUM. 367 



9. COSMARIUM QUADRATUM Ralfs. 



Plate LXXXVI. Figs. 11. and 12. 



Cliar, Fronds about twice as long as hroad. Segments qua- 

 -drate, in front view sliglitly compressed^ smooth. 



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



Hab. Rusthall Common, near Tunbridge Wells : Mr, 

 Jenner. Dolgelly : Mr. Ralfs. 



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. 



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

 Wells, p. 196. Cosmarium Cucurbita Desm., Xo. 1103. 



Hab. Dolgelly : Mr. Ralfs. Ashdown Forest and 

 Greatham bogs, near Pulborough : Mr. Jenner. 



This species approaches rather closely to Cosmarium cylin- 

 drum E.alfs, 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. CLOSTEKIUM Nitzsch. 



Char. Fronds elongated, mostly crescentic, sometimes con- 

 jugating ; each formed of two similar segments, lohich 

 unite loithout constriction, and the free extremity of each 



