1?Y G. i. PLAYFAIR. 505 



111 this form, the cells are broader aud the heterocysts some- 

 times narrower than in the type (cell. diam. 4-6, heterocyst. 6-8, 

 gonid. 8-10/x); c/'. Hornet et Flahault, Kevis. d. Nostoc., p.'233; 

 Tilden, Minnesota Algtp, i., p. 193, PI. ix., f.l9. 



Anab.ena laxa \ar. hortkxsis, n.var. (PI. liv., f. 15, 16). 



Forma heterocystidibus cylindiaeeis : g()ni(his cvlindraceis 

 elongatis. 



Cell. diam. 6-7, alt. 8-12; heterocyst. 7, alt. 14-16; gonid. 7, 

 alt. 33//. 



Botanic Gardens, Sydney (158). 



Cf. iSpha'rozyc/a {Anahfcua) Jaxa Habenhoi'st, Fl. I'^ur. Alg., ii., 

 p. 193; Tilden, I.e., p. 192, PI. ix., t'.i8. In the type, the hetero- 

 cysts are spherical, and the gonidia are shorter. Cell-contents, 

 in our form, pale blue, in the heterocysts and gonidia a deeper 

 blue. Ptabenhorst, I.e., gives '■^frichomatibtis . . . liUeo-fernyineis" 

 and ^'sporis . . so.tjirate luteo-virldihus^'' for the type. 



(jienus C Y L I X D R O S P E R M u M Kiltz. 

 Cylindrospekmum stagnale v. australe, n.var. (PI. liv., f. 17-21). 



Forma cellulis cylindraceis, disjunctis, apicibus truncatis ; 

 heterocystidibus oblongo-cylindraceis vel conicis ; gonidiis ob- 

 longis vel oblongo-cylindraceis, apicibus rotundatis, cvtoplasmate 

 pulchre cyaneo vel dilute viridi. 



(1). Cell. diam. 4-5, alt. 5-10 (plerumque 7-8); heterocyst. diam. 

 4-6, alt. 8-11; gonid. diam. 9-13, alt. 18-30/x. Lismore (302). 



(2). Cell. diam. 3, alt. 4 10 (plerumque 4-5); heterocyst. diam. 

 3-4, alt. 7-14; gonid. diam. 7^-9^, alt. 11-12//. Lismore (306). 



Cf. G. S. West, Br. Frw. Alg., p.328, f.l50; Tilden, Minnesota 

 Algie, i., p. 198, PI. X., f.2. The type has oblong cells; in this 

 form, they are quadrate or cylindrical. 1 found it once (sample 

 306) as a grey-green, foliaceous, mucous stratum at the grassy 

 edge of a swampy pool. Though the cells and heterocysts of the 

 interlaced trichomes were all of the same size and shape, there 

 were intermingled in this one stratum three distinct tyjjes of 

 gonidia. The most frequent answered exactly to C. stagnale; 

 another I have already described as C. rectangalare; and the 



