BY G. I. PLAYFAIR. 625 



radiis glabris, ellipticis 4, paullo intra marginem orientibus, 

 cruciatirn dispositis, ornatee. Membrana glabra. 



Long, c.proc. 27, s proc. 19; lat. c.proc. 27-38; lat. corp. 22. lat. 

 isth. 18^. 



Botany (17). 



With this species compare St. nudibrachiatum Borge, Alg. 

 Regnell. T.4, f.20, which is very much larger and seven-rayed, 

 the rays bifid. Of that, a var. Victoriense G. S. West, 10-radiate, 

 is reported from Victoria by Hardy in his Frw. Alg. of Vict. 

 (Vict. Nat. xxii. p. 72). Another somewhat similar form is St. 

 sublaevispinum West & West, Desm. U.S. T. 18, f. 20-22, with less 

 prominent body and narrower isthmus. 



St. brachiatum Ralfs. 



Long, c.proc. 21-26, s.proc, 15; lat. c.proc 25-30; lat. isth. 7/x. 



Botany (17). 



The essential difference between this species and St. aureolatutn 

 supra, is that the latter has a well-defined globose body into which 

 the rays are, so to speak, inserted. In this form the rays are 

 prolongations of the sides of the semicell which has no distinct 

 body. On the other hand St.laevispinum Bissett (Journ. R. Micr. 

 Soc. iv. T.5, f.5) has apparently no distinct rays but only attenua- 

 tions of the body. Compare St. sublaevispinum West & West, 

 Desm. U.S. T.18, f. 20-22, which is very probably a young form 

 of St. brachiatum. St. laevispinum forma Sydney ensis Rac, 

 Desm. Ciast. T.2, f. 10, is identical with St. brachiatum var. 

 longipedum Rac, Desm. Tapakoom. f.20. 



St. orbiculare (Ehr.) Meneg. var. germinosum, n.var. (Plate 



xii., fig.9). 



Forma medio sinu lineari extrorsum ampliato profunde con- 

 stricta. Semicellula? subtriangulares; angulis basalibus late- 

 rotundatis; lateribus ad apices convergentibus, plus minus con- 

 vexis; apicibus late-rotundatis; lateribus processibus glabris, 

 brevibus, bifidis instructis, ad angulos basales singulis, infra 

 apices binis, ad media latera binis. A vertice semicellula? trian- 

 48 



