JJ'es/ : Phytoplankton of English Lake District. 291 



as some of his other observations point to similar misconcep- 

 tions. He describes the librillar structure of the mucous 

 envelope of certain Desmids as ' spines.' 



We would point out that the cells of the FAidorina-^oXowy 

 are arranged more closelv. and much more regularly than those 

 of SpJurrocystis, and that each cell frequently contains several 

 pyrenoids. Moreover, the bases of the cilia, where the}' pass 

 through the mucous envelope, can always be seen in Eudovina, 

 even in badly preserved specimens. 



Fig. 6. A.-D., Elakatothrix gelatiuosa Wille from the plankton of 

 Wastwater. A. and B., Colonies, x 200 ; C, portion of colony, \ 500 ; 

 D., ver\- small colony, x 500. E., Staurastnmi brevispiuuui Breb. forma 

 major from the plankton of Brothers" Water, x 500. 



iQ. Elakatothrix gelatixosa Wille in ' Biol. Centralbl.', 

 XVIII.. iSqS. 



This interesting Alga has only previously been observed in 

 the lakes of Norway. It is not uncommon in the plankton of 

 Wast water, more especialh* in August. September, and October, 

 but the British speciniens do not exactlv agree with those 

 described from Xorway. The cells are slighth- narrower, 

 and their disposition within the en\'eloping mucus is often 

 somewhat irregtilar. although their long axes are arranged 

 more or less lengthwise m the colony. The exterior of the 

 mucous in\'estment is \'ery lirm and tough, and the colonies 

 biave the general form of a somewhat irregular spindle. Long. 



■1909 Aug. I. 



