44 r. E. FEITSCH. 



doliformibus, singulis, contentu exiguo, diametro cellularum sequalibus ; sporis in 

 catenis dispositis, plerumque ab heterocystis remotis, cylindricis, interdum leniter 

 curvatis, diametro 4-8plo longioribus, finibus rotundatis vel modice aciitis, cyto 

 plasmate cum granulis numerosis, membrana tenui levi. 



Diam. cell. veg. = 5 "5-7 /a; diam. heterocyst. = 5' 5-7' 5^; lat. spor. = 7*5-9 /a; 

 long. spor. = (l9)-48-58;u,. 



Hab. — Gap pond, Winter Harbour, February 20tli, 1904. 



This species belongs to the section Dolichospermum and appears to be most 

 nearly allied to A. catenula (Kiitz.) Born, et Flah. It differs from the latter in 

 being epiphytic, in the occasional presence of a narrow sheath, in the frequently 

 oval shape of the vegetative cells (fig. 118), and especially in the spores. The 

 latter do not show the faint constriction characteristic of A. catenula, and are 

 longer and narrower (figs. 118-120) ; the ends are also different. The spores of 

 A. catenula var. americana Collins, are somewhat more like those of A. antarclica, 

 but there are still appreciable differences, as the spores of the latter cannot be 

 described as strictly cylindrical. 



Genus Nodularia Mertens. 



65. Nodularia spumigena. 



Var. MINOR var. nov. 



(PL IL, figs. 104-108.) 



Nodularia spumigena Mertens, in Jiirgens. Alg. Aquat. xv. (1822), No. 4; Bornet et Flahault, torn, cit, 

 pp. 245-246. 



Fills solitariis, subrectis vel varie flexuosis, elongatis, finibus non attenuatis ; 

 vaginis tenuissimis, hyalinis, arctis, ssepe evanescentibus ; trichomatibus leniter 

 torulosis ; cellulis planis plerumque longitudine duplo ad triplo latioribus, membrana 

 tenui hyalina, contentu granulis ssepe magnis repleto ; heterocystis transvcrso- 

 ovalibus vel deplanatis, plerumque solitariis, sed interdum 2- vel 3-seriatis, paulo 

 latioribus quam cellulis vegetativis, membrana modice incrassata, contentu serugineo 

 homogeneo ; sporis ? 



Diam. cell. veg. = 5-5 ' 5 /a ; long. cell. veg. = 2 • 5-3 ' 5 /a ; diam. heterocyst. = 

 6-5-7 ju,. 



Hab. — Gap pond, Winter Harbour, February 20th, 1904 (epiphytic on Phor- 

 midium); dry ponds, Winter Quarters, February, 1902. 



This form differs from var. genuina Born, et Flah., of N. spumigena Mertens, 

 chiefly in its smaller dimensions ; the trichomes are, however, not nearly as torulose 

 as those of the type, and the thin sheath is highly diffluent, being often wanting. 

 The heterocysts of the Antarctic variety agree very closely with those of var. 



