506 XEW AND RARE FRESHWATER ALG^E, 



third seems to be a form of C. Goetzei Schmidle. T have 

 accorded these forms specific rank, as it is the general practice, 

 and cumenient for classification: besides, what should be char- 

 acteristic of a species in these plants, if not the shape of the 

 gonidia! Nevertheless, their being intermingled in one mucous 

 stratum indicates that they are merely allotropic forms of one 

 plant, brought about by different modes of growth. 



Most of the trichomes in the mucus were merely interlaced, 

 but here and there they were closely coiled in a spiral manner 

 (PL liv., f.21). This is not uncommon in free-swimming filaments 

 of the plankton, but very unusual in mucous strata. 



Cylindrospermum rectangulare Playf. 



(1). Gonidia thin-walled, rectangular: heterocysts oblong or 

 acutely conical. 



Cell. diam. 3, alt. 4-10; heterocyst. 3-4, alt. 7-14: gonid. 4, 

 alt. 14/x. 



Lismore (306). (PI. liv., f.22). 



(2). Gonidia thick- walled, cylindrical: heterocysts oblong. 



Cell. diam. 4, alt. 5-10 (plerumque 7); heterocyst. 4-6, alt. 8|- 

 \0h; gonid. diam. 9i-12, alt. 29-38/x. 



^ Lismore (302). (PI. liv., f. 23). 



Cf. Frw. Algfc of the Lismore Distr., these Proceedings, 1915, 

 p.349, f.A. 



Var. PARVICELLULA, n.var. (PI. liv., f.24, 25). 



Forma cellulis minimis, plerumque adpressis, quadratis vel 

 diametro brevioribus, cellula apicali acute-conica; heterocystidi- 

 bus oblongis; gonidiis interdum lateribus paullo arcuatis. 



Cell. diam. 2-2|; heterocyst. 3i, alt. 7; gonid. 10, alt. 24/x. 



WoyWoy(270). 



In a gathering kindly sent me by Mr. A. H. 8. Lucas. The 

 cells are unusually small for plants of this family: it should be 

 noted, too, that the gonidia are not any smaller on that account. 

 The walls of the latter were incrassate, rufescent and scrobicu- 

 late; this takes place with age, however, in the gonidia of every 

 species. 



