342 DESMIDE^, 



mostly bicrenate. Endochrome frequently bipartite, in 

 the transverse vieiv stellate, not filling entirely the cavity 

 of the cells. Reproduction by bodies analogous to zoo- 

 spores. 



Derivation, From Ss(t/jLos, a bond. 



a. Filaments ivith tivo angles. 

 * Mucous sheath very evident. 



1. Desmidium cylindeicum Grev. 



Plate LXXXIII. Figs. 1, 2. 



Char. Filaments stout, somewhat compressed, with two bi- 

 crenate angles. Crenatures strongly marked. Cells 

 rather longer than broad, connected by a thickened border, 

 mucous sheath very evident. Endochrome four or Jive 

 rayed. 



Grev. Scot. Crypt. Flor. t. 293.; Desmar, n. 1110.; Harv. 

 in Manual, p. 196. Didymoprium Grevillei Xviitzing, 

 Phyc. Gener. Desmidium cylindricum Ralfs, in An- 

 nals, vol. xi. p. 378. pi. viii. fig. 1. 



Hab. Scotland : Dr. Greville. At the bottom of shallow 

 pools and ditches, Appin : Captain Carmichael. In old 

 peat pits about Dolgelly, North Wales ; sparingly near 

 Penzance : Mr. Ralfs. In a watercourse on Cliiltington 

 Common, near Pulborough, Sussex : Mr. Jenner. Clies- 

 hunt : A. H. H. In Caragh Lake, Kerry : Mr. An- 

 dreios. Bog holes, co. Meatli : Mr. Moore. 



The above description embraces all the essential characters 

 of the species which may be regarded as the type of the 

 genus. In consequence of the sj^iral twisting of the filaments 

 the crenatures are much more perceptible in certain cells than 

 in others ; they are most strongly marked as a rule at about 

 every tenth cell, gradually diminishing from these towards 

 the central cells^of the series, where they are much less ap- 

 parent, and where the extremities of the crenatures, instead 



