426 TUFTS COLLEGE STUDIES, VOL. II, No. 3 



vata Gotz, 1897, p. 114, figs. 23-28; an Ectospcrma clavata 

 Vaucher? Filaments 77-110 p. diain.; oogonia one or two, ses- 

 sile, 55-75X80-110 /A, narrowly ovoid, erect, with a short and 

 broad vertical beak; oospore of same shape, 50-65X65-90 /x 

 with a red central spot and triple membrane ; antheridium soli- 

 tary beside a single oogonium or between two oogonia, circi- 

 nate, on a straight or recurved pedicel ; zoospores I25-I5OX 

 135-175 /"., in broadly clavate sporangia ; cilia uniformly distrib- 

 uted. In ponds and ditches. Cal. Europe. 

 The three species, V. repens, V. sessilis and V. orthocarpa are 

 certainly closely related, but Gotz, who has studied them more 

 than any other observer, considers them distinct. Beside the 

 differences in dimensions of filaments and dimensions and shape 

 of oogonia, he notes physiological characters, which it is not 

 practicable to give here in detail. As far as Vaucher's descrip- 

 tion of Ectosperma clavata goes, it would seem to apply to any 

 zoosporiferous Vaucheria ; Gotz does not state why he identi- 

 fies E. clavata with V. orthocarpa Reinsch, except that the sex- 

 ual organs' in his plant agree with Reinsch's description and 

 plate ; but Vaucher knew the zoospores only. , 



9. V. HAMATA (Vauch.) De Candolle, 1805, p. 63; Walz, 

 1866, p. 148, PI. XII, figs. 12-16; Wolle, 1887, p. 152, PL 

 CXXVIII, figs. 8-10. Filaments 40-60 p. diam., oogonia soli- 

 tary, 75-90X60-75 p., ovoid to convex-concave, borne on the 

 shorter division of an apparently forking branch ; the longer 

 division recurved, bearing the hooked or circinate antheridium ; 

 or an oogonium on each division, the antheridium between ; an- 

 theridium in a plane at an angle to that of the oogonium ; 

 oospore closely filling the oogonium, with quadruple membrane 

 and a dark brown or blackish central spot ; the membrane of 

 the oogonium falling with the oospore, but not gelatinizing ; 

 aplanospores formed in terminal, somewhat clavate sporangia, 

 when ripe ejected from the latter. On moist ground or sub- 

 merged. Washn., Cal. Europe. 



10. V. TERRESTRis (Vauch.) De Candolle, 1805, p. 62 ; 

 Walz, 1866, p. 149, PL XIII, figs. 18 and 19; Wolle, 1887, p. 

 153, PL CXXIX, figs. 1-8; P. B.-A., No. 78. Filaments 

 50-80 fj. diam.; oogonium usually solitary, 85-125X60-100 /*, lat- 

 eral on a short branch, on the summit of which is the curved or 

 circinate antheridium, about 20 //. diam.; oospore globose to 

 plano-convex, with -quadruple membrane and numerous brown- 

 ish spots ; the membrane of the oogonium remaining attached 

 to the oospore and falling with it, gelatinizing and ultimately 



