ZYGNEMA. 145 



Conf. jugalis Dilhv. t. 5. ; and C, nidda, t. 4. f. A. B. Z. 

 deciminum Harvey, 1. c. p. 362. ; also in Manual, p. 143. 



Hah. Chcshunt and Epplng Forest : A. H. 11. In a ^ 



l^ond between Kamslye Kocks and Broadwater Forest ; ^^^ 



Henfield Common; and in a pond at Hill Park, near /-^^'^ 



Westerliam, Kent : Mr. Jenner. / ^ 



This is a very pretty species, and also very distinct, the "^'^ 

 crosses described by the spires at once serving to distinguish 

 it from all others belonging to this division of the genus 

 Zygnema. Filaments frequently almost black. 



c. Spires single. 



12. Zygnema quininum Ag. 



Plate XXYIII. Figs. 1, 2. 



Char. Filaments of rather larger diameter than those of 

 Z. deceminum. QqW^ longer than broad. S])iYe performing 

 about three revolutions in each. Sporangia acutely oval, not 

 producing inflation of the cells in ichich they are lodged. 



Conferva porticalis Miiller, Nova Comment. Petropolitana, 

 pars 3. p. 90. Conjugata porticalis Vaucher, Hist, des 

 Conf. pi. 5. fig. 1. ; Dillw. t. 3. lower figure. ^Uc £. 



Hab. Everywhere common throughout Britain. ^<v^y 



^' This conjugata, already described and observed by ^ 



Miiller, is perhaps the most common of all those of the same _ 

 family ; its spires are formed of brilliant grains united by a y" ' 

 thread or a tube. Miiller compares them to porticos, since ^^ 

 in a certain state of their developement they have the form of /^J« 

 a semi-ellipse." — Vaucher. The specific name of quininum J* 

 bestowed upon them by Agardh is intended to express as well 

 as Miiller's of porticale, which ought properly to have been 

 retained on account of its priority, the form described by 

 each turn of the spires. 



13. Zy^gnema varians Hass. 

 Plate XXIX. Figs. 1, 2, 3, 4. 



Char. Filaments of somewhat less diameter than those of 



.tA 



