GONIOCYSTIS. 349 



2. SPHiEROZOSMA EXCAVATUM. 



Plate LXXXIV. Fig. 2. 



Char. Cells longer than broad, excavated laterally, icith ttvo 

 (jlands or teeth at each margin. 

 Schistochilum excavation Ralfs, IMS. ; Jenncr, In Flora of 

 Tunbridgc Wells, p. 192. 



Ilab. In a boggy spot near Cross in Hand, opposite to 

 where the road branches to Hailsham ; bogs at Fisher's 

 Castle, and in a pond between Ranislyc and Broadwater 

 Forest : Mr. Jenner. 



A very distinct and interesting species. 



Section il. 

 Frond not forming filaments. 



54. GONIOCYSTIS Ilass. 

 Char. Cells angular. 



Derivation. From jcovta, an angle, and Kvcrri9, a cell. 



Section i. Trigonocystis Ilass. 



Char. Cells with three angles. 



Derivation. From TpLywvov, triangular, and kvctls, a cell. 



1. Trigonocystis orbicularis Ilass. 



Plate LXXXIV. Fig. 7. 



Char. Frond smooth, suhorhicular. End view triangular. 

 Angles obtuse. 

 Staurastrum orbiculare INIeneghini, Synop. Dcsmid. p. 225. 

 Desmidiiim orbiculare Ehr., Infus. p. 141. tab. 10. fig. 9. 

 Staurastrum orbiculare Ralfs, in Annals, vol. xv. p. 152. 

 pi. X. fig. 4. a. b. c. ; Jenner, in loc. cit. p. 192. 



