ZYGNEMA. 145 



Conf.jugalis Dillw. t. 5. ; and C. nitida, t. 4. f. A. B. Z. 



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



Hab. Chcsliimt and Epping Forest: A. II. H. In a 



jjond between Eamslye Rocks and Broadwater Forest ; 



Henfield Common ; and In a pond at Hill Park, near 



Westerham, Kent : BIr. Jcnner. 



This is a very j^retty 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 



Zygncma. Filaments frequently almost black. 



c. Spires single. 



12. Zygnema quininum Ag. 

 Plate XXVIII. Figs. 1, 2. 



Char. Filaments of rather larger diameter than those of 

 Z. deceminitm. Cells longer than broad, '^^ivc j) erf or ming 

 about three revolutions iyi each. Sporangia acutehj oral, not 

 j)roducing inflation of the cells in ichich they are lodged. 

 Cuifervaporticalis JMiiller, Nova Comment. Petropolitana, 

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

 Conf. ]A. 5. fig. 1. ; Dillw. t. 3. lower figure. 

 Hab. Everywhere common throughout Britain. 



" Tliis conjugata, already described and observed by 

 IMiiller, is perha23S the most common of all those of the same 

 family ; its spires are formed of brilliant grains united by a. 

 thread or a tube. IMiiller compares them to porticos, since 

 in a certain state of their developement they have the form of 

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

 bestowed upon them by Agardli 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. Zygnema varians Ilass. 

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



Char. Filaments of someichat less diameter than those of 



