BY G. 1. PLAYPAIR. 836 



Var. iNERMis, n.var (PI Ivii., f.l2, 13). 



Forma sine spinis. Ccenob. (4 cell.) 15-20 x 11-12/a. 



Botany (145); Lismoie (260); Enogf];era. 



1^ ot y ecornis Ralfs, Brit. Desm., T.31, f.l2h [ = <S'f. hijngus 

 (Turp.)]. In the latter, all the cells are of the same size, and 

 are regularly or irregularly oval. In var. iuermis, the outer cells 

 are slightly smaller than the inner, the latter also being strictly 

 cylindrical, with parallel sides and rounded ends. 



Sc. DENTICULATUS var. GRACILIS, n.var. (PI. Ivii., f. 14). 



Cellulie gracillimse, lineares, elongatai, lateribus parallelis. 



Crenob. (4 cell.) long. 12-21, lat. 12-20; cell. diam. 3-5/x. 



Botany (17, 50, 95, 145, 155); Guildford (70); Centennial Park 

 (133); Lismore(187). 



Much more common here than any other form of >Sc. denticu- 

 latus. The cells ai-e linear and very slender, with parallel sides, 

 ccenobia generally 4-celled. 



Var. oPOLiENSis (Richter) mihi. 



Ccenob. (2 cell.) s.sp. long. 8-12, lat. 12-15; sp.long. 6-10/t. 



Botany (50, 108); Parramatta (136); Enoggera. 



Syn., Sc. oj)oliensis Richter, Phycotheca universalis, No.686; 

 Sc. ({iiadricnudo, var. opolieiisii< (Richter) W. & G. 8. West, Frw. 

 Alg. Ceylon, p. 197, PL 17, f.l6, 17. The apical denticulations 

 stamp this form as a variation of Sc. denticulatus. Tlie presence 

 of the long, terminal spines in <Vc-. hi/i^trix var. annatus Chodat 

 (also found here) shows that they are not necessarily indicative 

 of Sc. qiiadricauda. 



Var. AUSTRALis, n.var. (PI. Ivii., f. 15). 



Cellula; dentibus singulis ad apices instruct*; long. s. dent. 16, 

 lat. 6/7,. Collector. 



Forms of Sc. denticulatus generally have two or three denticu- 

 lations at the apices; in this form, there is one only. C'/". G. S. 

 West, Br. Frw. Alg., p.220, fig.92.r. 



SCENKDESMUS SECURIFOKMIS, n.sp. (Pi. Ivii., f.l6, 17). 



Celluhe exteriores (interdum etiam mediante) modice securi- 

 formes, spinis luillis. 



