- 178 - 



85. S. orbiculare Menegh. Synops. Desm. in Linnæa 1840, p. 225; 

 Ralfs Brit. Desm. 1848, p. 125, t. XXI, f. 5. 



Var. depressum Roy et Biss. Le. p. 237, t. 268, f. 14. 

 Long. 21—25.//; lat. 21—25/;.; lat. isthm. 7,5/*— 8,6/*. 

 With the preceding species. 

 Area (of type and varieties): Ubiquitous. 



86. S. Bieneanum Rabenh. Alg. No. 1410; West & G. S. West in 

 Journ. Roy. Micr. Soc. 1896, p. 158, t. Ill, f. 27. S. orbiculare var. 

 Bieneanum Rabenh. Flor. Europ. Algar. Ill, p. 200. 



Var. orientale West. & G. S. West, n. var. (Tab. nostr. III, fig. 29.) 



Var. minor, dorso semicellulamm corrvexo (non retuso in medio); 

 membrana glabra. 



Long. 25/7.; lat. 22,5/;; lat. isthm. 6/;. 



Only one specimen of the Siamese plant was seen and provisionally 

 we place it as a variety of S. Bieneanum Rabenh. It is very probable 

 that S. Bieneanum var. orientale will ultimately prove to be a distinct 

 species. 



Area (of type): Europe, N.America, E. Africa, Madagascar, Siberia, Japan, 

 Samoa, New Zealand and Australia. 



87. S. Zahlbruckneri Linkern, in Ann. des k. k. Naturhist. Hofmus. 

 Wien 1900, Bd. XV, Heft 2, p. 125, t. VI, f. 41-43. 



Var. mamillatum West & G. S.West, n. var. (Tab. nostr. III, fig. 35 

 -37.) 



Var. cellulis in ambitu subeircularibus; semicellulis subdepressis 

 semicircularibus, apieibus latissime rotundatis; angulis bilobulatis, 

 lobulis valde mamillatis, iis semicellulæ alterius interdigitatis cum 

 iis alterius; a vertice visis lateribus subrectis. 



Long. 92 - 95 t i\ lat. 80—82 ju; lat. isthm. 27—28,5 //. 



Numerous examples of this fine Staurastrum were seen. The typical 

 form was recently described by Lütkemüller from the Ningpo Mountains 

 in Central China. The Siamese variety is relatively shorter and possesses 

 more rounded semicells; the angles are more deeply lobed and distinctly 

 mamillate, the mamillate lobes of one angle fitting into those of the other, 

 thus causing a striking peculiarity of the sinus, the aperture of which is 

 rarely visible. 



The cell-wall is very much . thickened at the mamillate angles and 

 shows a marked lamination. Sometimes a few lateral wart-like excrescences 

 are present on the opposed faces of two interdigitating lobes of the angles. 

 The cell- wall is strongly punctate as in the typical form. 



In stagnant water in the jungle. 

 Area (of type): Central China. 



88. S. alternans Bréb. in Ralfs Brit. Desm. p. 132, t. XXI, f. 7. 

 Long. 26 u; lat. 25/^; lat. isthm. 8,5«. 



