550 PLANKTON OF THE SYDNEY WATER-SUPPLY, 



Fig. 24. — St. volans var. triijonum, n.var. (x700). 



Fig. 25. urbiculare v&r. protract iim, n.var. (x528). 



Fig. 26. mixed form: type (a)-|-var. protiactuni (b), 



both budding into processes (var. (jermiiiosuin Playf.). 



The fullgrown form, St. U^itacanthum Nord., is common 



in a tank in the Botanic Gardens, supplied solely by 



Sydney water ( x 528). 



Fig. 27. orbiculare var. planhtomcMui, n.var. (x 700). 



Figs. 28-29. — Eu. quadratu in Nord. var. intermedium Playf., antea 



1908, p. 609. (29) End view ( x 528). 

 Fig. 30. — var. perornatum Playf., I.e., p. 608, end 



view (x 528). 

 Fig. 31. — Micr. truncata mixed form: (a) var. decemdeviatn 



(Nag.) + (ft) var. innsa (Breb.) (x430). 



Plate Iv. 

 (Figures magnified 350 diams., unless marked otherwise.) 



Fig.l. — Feridinium tabulo.tum var. (iranulosum, n.var. 



Fig. 2 — — ■ another cell with granules in lines ; (a) mem- 

 brane ( X 700), (b) diagram of hypovalve. 



Fig. 3. another specimen ; ((() obverse, (b) reverse, (c) 



diagram of epivalve, (d) diagram of hypovalve. 



Fig. 4. another cell, strongly hut irregularly granu- 

 late ; (a) obverse, (6) reverse, (c) hypovalve, (d) epivalve, 

 (e) epivalve of another cell, (/) membrane intermediate in 

 character between var. gmnulosum and var. Westii{x 700). 



Fig. 5. > var. Westii (Lemm.) forma australis (x450); 



(a) obverse, (b) reverse. 



Fig. 6.' a smaller, less corrugated cell ; 



diagram of epivalve (x528). 



Fig. 7. another cell, obliquely tilted, show- 

 ing the apex of var. 2;i/.s/7/i/m (Penard) (x528). 



Fig. 8. ■■ ■ — another cell, hypovalve (x528). 



Fig. 9. . — another cell, hypovalve (x350). 



Fig. 10. ■ var. zonatuiii, n.var. 



Figs. 11-12. two slightly different hypovalves. 



Fig. 13. var. hierocjlyphiruw, n.var. 



Fig. 14.^ var. ovatum, n.var. 



Figs. 15-16. var. irdermedivm , n.var., two forms (x528). 



Fig. 17. var. afrirnmim (Lemm.);(r7) obverse, (b) re- 

 verse (x700). 



Fig. 18. — -var. ravdntiim, n.var., two forms; (a) ob- 

 verse, (b) reverse (x700). 



FigN. 19-21. var. /h/.s/7/i/;» (Penard) forma mnr.<<a, three 



cells (x 700). 



F'ig.22. var. inconspicmnn (Ticniin.) forniji (x700). 



