BY G. I. PLAYFAIR. 623 



St. patens Turn., var. coronatum, n.var. (Plate xiii., fig. 11). 



Semicellulae processibus brevibus glabris bifidis 6 in apicibus 

 concentrice ordinatis, cetera ut in forma australica. 



Long.c.proc. 36-56, s.proc. 24-48; long. proc. 6-8; lat.c.ac.54 57, 

 s.ac. 31-37/i. 



Botany (2, 37), Sydney Water-supply. 



Forma obesa, n.f. (Plate xiii., fig. 12). 



Semicellulai longiores, sursum tumida?, dorso convexse, pro- 

 cessibus lateralibus latioribus, horizontaliter dispositis, aculeis 

 brevioribus. 



Botany (7). 



The six faint granules arranged concentrically in end-view of 

 forma australica have here developed into six short, smooth, bifid 

 processes, the double granules nearer the angles remaining 

 unchanged. The same rule of development obtains in many other 

 desmids, perhaps in all those furnished with short, smooth pro- 

 cesses such as St. armigerum, etc. First a granule or denticula- 

 tion, then a delicate spine, finally a smooth, bifid or'trifid process, 

 is the order. It may be observed also in St. orbiculare var. 

 germinosum mini, and St. submonticulosum Roy & Bissett. St. 

 patens, as found here, has two shapes in front-view — the one 

 with flat apex and narrow constricted processes turned up well 

 from the horizontal; the other (forma obesa mihi) inflated above, 

 with broader, less constricted processes pointed horizontally. The 

 long spines, I find, are two or three in number quite indifferently. 

 Hardy says of var. planktouicum (I.e. p. 7 3) — "This variety 

 differs chiefly in the three large spines at each angle instead 

 of the two possessed by the Indian forms." As the spines 

 vary, it would perhaps be safer to rely on the end-view-, which, 

 with its almost straight sides and produced angles, is quite 

 different from Turner's figure or description. 



St. Sebaldi Rein. /3 altum (Boldt) West & West, N. Amer. Desm. 

 p. 267, forma pusilla, n.f. (Plate xiii., fig. 13). 



Forma dimidio minor quam /3 altum, dorso minus convex'o, 

 verrucis apicalibus minus prominentibus. 



