BRITISH DESMIDIE^.. 16? 



Frond bright green, stout, distinctly visible to the naked eye. Innately curved, 

 five or six times longer than broad, extremities tapering, ends rounded ; lower 

 margin very concave, inflated at the middle ; fillets several, one to three more 

 distinct than the rest ; vesicles few, large, and disposed in a single longitudinal 

 series. The empty frond, colourless and vrithout a suture at the middle, col- 

 lapsing w^hen dried. 



Closterium monilifermn is smaller than C. Lunula and more curved, and it 



may ahvays be distinguished by the inflation at the middle of its lower margin ; 



its vesicles form a single series, a character which separates it also from 



C Ehrenbergii. 



Length of frond from ^^ to ^ of an inch ; greatest breadth from 3^^^ to 

 1 



Tab. XXVIII. fig. 3. a. frond with endochrome ; b. empty frond. 



7. C. Jenneri ; frond crescent-shaped, generally slightly con- 

 stricted at the suture, when empty colourless, rapidly tapering; 

 ends very obtuse ; vesicles in a single series. 



Closterium moniliferum, Ehr. Infus.t, 5. f. 16. n. 6, 7 (1838). 

 Sussex ; Surrey ; and Hampshire, Mr. Jenner. Penzance, J. R. 



Frond smaller than that of Closterium moniliferum, much curved ; extre- 

 mities tapering ; ends rounded. There is generally a slight constriction at the 

 suture. Fillets two or three. The empty frond colourless and without 

 markmgs. 



Closterium Jenneri is more curved than C. moniliferum, and there is no 

 inflation of its lower margin. It is more curved than C. Leibleinii and 

 C jyiance, and its ends are far more obtuse than theirs. 



Length between ends of frond -^^ of an inch ; breadth at suture -yttq- 



Tab. XXVIII. fig. 6. a, b. fronds with endochrome ; c. empty frond. 



8. C. Leibleinii (Kiitz.) ; frond smooth, crescent-shaped ; extremities 

 much attenuated and subacute at the apex ; lower margin slightly 

 inflated at the middle ; vesicles in a single row. 



/3. More slender, the central inflation less evident ; empty frond 

 of a deeper colour and its central suture distinct. 



Closterium Lunula, Leibl. Fl. 1827, p. 259. according to Kilts;. 



Closterium Leibleinii, Kiitzing, Synop. Diatom, in Linncea 1833, p. 596 ; 



Phrjcol. Germ, p. 130. Brebisson, Alg. Fal. p. 58. t. 8. Meneghini, 



Synop. Desmid. m Linncsa 1840, p. 232. 



Cheshire, Mr. Sidebotham. Albourn, Framfield, and Hastings, Sussex ; 

 and Reigate, Surrey, Mr. Jenner. Penzance and Dolgelley, J. R. Rochdale, 

 Mr. Coates. Aberdeen, Mr. P. Grant. Shirehampton near Bristol, Mr. 

 Thwaites. 



Germany, Kiitzing. Falaise, Brebisson. 



Frond small, crescent-shaped, stout, about four to eight times as long as 



