156 CONJUGATED: 



I have only once met with this. If a condition of any, it 

 must be of the preceding species. 



b. Sporangia formed in every cell. 



34. ZYGNEMA MIRABILE Hass. 

 Plate XXXV. Figs. 1, 2, 3. 



Char. Filaments equal to those of Z. commune in diameter. 

 Cells about six times as long as broad. Sporangia oval, at 

 first much elongated, and finally producing a slight in- 

 flation of the cells. 



Z. mirabile Hassall, MSS. 



Hob. Cheshunt and its vicinity : A. H. H. In the pond 

 between Tunbridge Wells Common and the Hurst 

 Wood ; in a pond at Burwash : Mr. Jenner. 



This remarkable Zygnema I have repeatedly met with in 

 the state in which I have described it, and which I believe to 

 be its perfect condition. Mr. Jenner states that he is con- 

 vinced that the cells are united, but that the connecting 

 tubes are so frail as usually to be destroyed before the 

 specimen is examined. Mr. Jenner's observation, however, I 

 feel assured applies not to Z. mirabile, but to some other 

 species ; for had the cells at any period been united, they 

 would have been clearly indicated, even in the absence of the 

 connecting tubes, by the occurrence of empty cells in number 

 equal to those which contained sporangia. Now I have said 

 that in this species all the cells contain sporangia. 



** 



Extremities of cells inverted. 

 a. Spires two. 



35. ZYGNEMA HASSALLII Jenner. 

 Plate XXXVI. Figs. 4, 5. 



Char. Filaments of nearly the same diameter as those of 

 Zygnema Grevilleanum. Cells five or six times as long 

 as broad. Spires two, laxly disposed, and crossing each 



