DESMIDIUM. 343 



of being pointed are truncate. This species, as well as in- 

 deed all the Desmidece, are most beautiful microscopic objects. 

 I do not see the necessity for instituting a new genus for its 

 reception. I have not, therefore, adopted that of Kiitzing ; 

 viz. Didymoprium. 



** Mucous sheath not apparent. 

 2. DESMIDIUM BORRERI Ralfs. 

 Plate LXXXIII. Figs. 9, 10. 



Char. Filaments slender. Cells biangular, inflated, elongated, 

 being about twice as long as broad. Endochrome^ue or 

 six rayed. 



Desmidium Borreri Ralfs, in Annals of Nat. Hist., vol. xi. 

 p. 375. t. 8. p. 4. Didymoprium Borreri Jenner, in 

 Fl. Tunbridge Wells, p. 192. 



Hob. Boggy ditch at Crom Bychan : Mr. Borrer. Llyn 

 y Cwyn : Mr. Borrer and Mr. Ralfs. In all peat bogs 

 near the outlet of Llanberris Lakes and near Dolgelly, 

 North Wales : Mr. Ralfs. , On Ashdown Forest near 

 Duddles Well ; in the great bog near Forest Row, and 

 at Chiltington Common, near Pulborough : Mr. Jenner. 

 Bog holes, co. Meath : Mr. Moore. 



This is one of the most graceful and easily recognised spe- 

 cies of the genus, remarkable principally for the great length 

 of the cells ; the endochrome in each cell is distinctly divided 

 into two masses, which arrangement imparts to the plant 

 somewhat the appearance of a Tyndaridea. 



The cells are somewhat inflated, and each resembles in 

 form two flower-pots juxtaposed by their mouths ; the rims 

 being represented by the crenatures of the cells, between 

 which passes circularly round each cell a superficial groove, 

 in the situation of which the cells at an advanced period of 

 their developement separate, and give issue to their granular 

 contents. Viewed transversely, the cells are spherical, with 



slight lateral projections. 



z 4 



