376 DESMIDE^E. 



tion of the vesicles containing the active molecules, which in 

 Closterium Trabecula as in all other Closteria hitherto de- 

 scribed are placed near to each extremity of the frond. 



13. CLOSTERIUM MARGARITACEUM JEhr. 

 Plate LXXXVIII. Fig. 5. 



Char. Frond cylindrical, narrow, two to eight times as long as 

 broad, somewhat quadrangular, often slightly constricted, 

 striated. Striae denticulated. Cells containing the revolving 

 particles distant from each extremity. 



Ehr. Infus. p. 93. pi. v. fig. 13. ; Jenner, inloc. cit. p. 196. 



Hob. Piltdown Common ; Warbleton ; and in the pond 

 between Ramslye and -Broadwater Forest : Mr. Jenner. 



A distinct and very interesting little species : it is some 

 eight or ten times smaller than Cl. Trabecula. 



14. CLOSTERIUM DIGITUS Ehr 

 Plate LXXXVIII. Fig. 4. 



Char. Frond broad, ovate, cylindrical, four or Jive times 

 as long as broad; transverse lines of division sometimes 

 triplex. Endochrome fasciated. Bands Jive or six, often 

 waved. 



Closterium digitus, AbhandL der Akademie d. Wissensch. 

 zu Berlin, 1831, p. 68. Pleurosicyos Myrio(po)dus 

 Corda, Almanac de Carlsbad, 1835, p. 182. t. 5. f. 68, 

 69. Cl. Digitus ? Menegh., 1. c. p. 236. 



Hob. Bogs at Fisher's Castle, Ashdown Forest ; Scrubbs, 

 Colebrook Park, and between Heathfield and Warble- 

 ton : Mr. Jenner. Aberdeen : Dr. Dickie. 



This is one of the finest and most distinct of the nume- 

 rous species described by Ehrenberg, whose figures of Clos- 

 teria are most beautiful and accurate, and whose descriptions 

 are not less so. The species of this genus being for the most 



