ZYGNEMA. 157 



other. Sporangia oval, large, and producing a considerable 

 inflation of the cells in which they are lodged. 



Zygnema Hassallii Jenner, in Flora of Tunbridge Wells, 



p. 182. 

 Hob. Cheshunt and Notting Hill : A. H. H. Sandhurst ; 



near the rock at Washington ; and at Hellingly : Mr. 



Jenner. 



Mr. Jenner has done me the honour to assign my name to 

 the above species, which is one of the finest and most distinct 

 of the Zygnemata. I encountered it several times during the 

 spring and summer of 1842, but not having then met with 

 it in a state of reproduction, I regarded the filaments as those 

 of Z. Grevilleanum, which, however, are usually furnished 

 but with a single spire, and in which the form of the conju- 

 gated cells is so different. 



b. Spire single. 



36. ZYGNEMA QUADRATUM Hass. 

 Plate XXXVII. Figs. 1, 2. 



Char. Filaments of rather less diameter than those of 7*yg- 

 nema Hassallii. Cells usually seven or eight times as long 

 as broad. Sporangia oval, large, and much elongated, 

 contained within quadrangular enlargements of the cells. 

 Tubes of communication prominent. 

 Zygnema quadratum Hassall, in Annals of Nat. Hist. 



vol. x. p. 41. 



Hob. High Beech ; Epping Forest ; Cheshunt ; and other 

 places : A. H. H. Pond at Ramslye : Mr. Jenner. 



This is one of the most distinct as well as curious of the 

 non-conjugating Zygnemata. It is by no means uncommon. 



37. ZYGNEMA INTERMEDIUM Hass. 



Plate XXXVII. Fig. 3. 

 Char, Filaments of rather less diameter than those of Z. qua- 



