BY G. I. PLAYFAIR. 621 



Long. c.ae. 36-4*2, s.ac. 26-30; lat. c.ac. 42, s.ac. 24-30; lat. isth. 

 6; long. ac. 6-9/*. 

 Botany (2). 



Var. intermedium, n.var. 



Sernicellulse, apicibus minus retusis, angulis apicalibus aculeis 

 minoribus binis munitis. Cetera ut in var. Botanicum. 



Long. c.ac. 36-42, s.ac. 24-28; lat. c.ac. 36-38, s.ac. 24-26; lat. 

 isth. 6; long. ac. 5-7/x. 



Botany (2). 



Genus Arthrodesmus Ehr. 



Ar. gibberulus Josh., in West k West, Frw. Alg. Ceylon, T.22, 



f.22. 

 Ar. ellipticus Playf., I.e. T.4, f.5. 



Var. ellipticus mihi, Proc. Linn. Soc. N. S.Wales, 1907, T.4, f.4. 



Genus Staurastrum Meyen. 



St. pseudosebaldi Wille, var. pectinatum, n.var. (Plate xiii., 



fig.9). 



Forma paullo gracilior quam forma typica, radiis longioribus, 

 spinis apicalibus non bifurcatis. 



Long. c.sp. 54, s. sp. 48; lat. 80/z. 



Botany (15). 



This form seems to suit the description and size of Wille's 

 plant, Norges Fersk. p. 45, and is not unlike the figure in T.2, 

 f. 30, considered as more or less diagrammatic. 



Var. planktonicum, n.var. 



Forma a fronte visa spinis nullis, marginibus denticulatis; a 

 vertice spinis nullis, marginibus corporis verrucis parvis ornatis. 



Long. 42-48; lat. 68-73 M . 



Sydney Water-supply (22). 



In front-view var. planktonicum somewhat resembles St. pseudo- 

 sebaldi* tonsum Nord., Frw. Alg. N. Z. T.4, f.4, but is triradiate 

 in end-view, not biradiate. It also bears a striking resemblance 



