182 Mr. Hassall^s Notices of British Freshwater Algce. 



fore, the reproduction of the Confervse is reduced to its simplest 

 form. 



The only purpose which can be recognised as being fulfilled by 

 the union of the filaments in M. genuftexa, &c. is, that thereby an 

 opening is efi'ected in the cells through which the zoospores can 

 escape on their separation from those cells. 



I now propose, therefore, that in the genus Mougeotia should 

 be placed only such species of conjugating Confervse as are cha- 

 racterized by the interesting fact of the non-formation of spo- 

 rangia. These species include the original and typical species of 

 the genus, M. genuflexa, M. compressa, as well as M. hrevior, 

 M. dubia, M. flava described in a previous paper, and M. erice- 

 tommy of which a detailed description will here be given. 



The genus Mougeotia may be thus defined : — 



Gen. Mougeotia. 

 Gen. char. — Filaments of equal diameter, rarely branched ; cells 

 usually conjugating; transference of endochrome rare; spo- 

 rangia none ; endochrome at first filling the cavity of the cell, 

 but subsequently contracting into an irregularly spiral thread ; 

 zoospores scattered without order through the colouring matter. 

 M. ericetorum. Filaments not unfrequently branched ; cells usually 

 about twice as long as broad, rarely uniting, but frequently 

 emitting elongated and irregular processes, which are usually 

 to be regarded as rudimentary ramuli ; endochrome frequently 

 becoming effused, generally from one cell into an adjoining one 

 in the same filament, but sometimes that from both cells passes 

 into a space formed between the two utricles. 

 It has elsewhere been stated that I had been induced, from the 

 detection of ramuH on some of the filaments, to consider Conferva 

 ericetorum as referable to the branched Confervse. It would 

 appear, however, on closer examination, that while it certainly, by 

 the not unfrequent occurrence of ramuli, exhibits a degree of re- 

 lation to those species, that yet its affinities with the conjugating 

 tribe are sufficiently strong to make it apparent that its proper 

 station is with these, and not with the branched species. 



When a communication is about to be set up between two cells 

 in the same filament, the opposed extremities of those cells are 

 first seen to become slightly inflated, to point somewhat and then 

 burst, effusing their contents sometimes into a space which is 

 gradually between the two cells, but at others the endochrome 

 of one cell passes directly into the cavity of the other. 



All the cells in a filament do not usually communicate with 

 each other at the same time, but at distant intervals ; and around 

 those cells between which a communication is about to become 



