The Freshwater Algae of A frica. 53] 



thai may be due to the solvenl action of the preservative. A large 

 Qumber of ill-defined bodies in the contents are probably food-reserves. 

 The membrane is invariably winged, the normal type of oospore having 

 a single median wing, appearing circular or elliptical when seen from 

 the surface (Fig. 16, B, a, and C), and as two blunt outgrowths in 

 optical section (Fig. 16, B, h, and d 1 ). In surface-view the wing shows 

 a fine crinkling, in the form of short wavy lines over its entire surface 

 (Fig. 16, B, a). Seen from the edge the part of the membrane, not 

 protruded into the wiiiir, has a crenate outline (Fig. 16, B, b, <l l ). 

 Side by side with this type, which was by far the commonest, other 

 oospores could lie found, in the same oogonium, in which the membrane 

 was protruded into three (Fig. 16, B, d) or even four (Fig. 16, B, c) 

 outgrowths, although such forms are not exactly common. 



In contrast to S. annulina (Roth), Ag., the new species is dis- 

 tinguished by (a) the customary irregular arrangement of the chloro- 

 phyll-apparatus ; (b) the usual occurrence of marked constriction at 

 the septa ; (c) the peculiar structure and mode of development of the 

 septa ; ((/) the mature oospores which differ very markedly from those 

 of the other species ; and (e) the development of the mature oospore 

 within a thin primary membrane. 



(/) CHAETOPHORALES. 



(1) CHAETOPHORACEAE. 



Genus STIGEOCLONIUM Kuetz. (MYXONEMA Fries). 



1. Stigeocloniwm prostratum, n. sp. (Fig. 17.) 



Thallus epiphyticus, plantis aquaticis adhaerens. Pars procumbens 

 thalli valde evoluta, filis ramosis dense aggregates, sed raro stratum 

 pai'enchymaticum crassitudine unaecellulae formantibus ; fila repentia 

 copiose ramosa, ramis singulis procumbentibus, saepe unilateralibus, 

 ex paene quaque cellula nascentibus, ramulis paucis et e paucis 

 cellulis constantibus; cellulis partium procumbentium rectangularibus, 

 1-2J plo longioribus quain latis, superne aut rectis aut convexis. Pars 

 adscendens exigua, e pilis sparsis hyalinis, saepe longissimis, acutis vel 

 obtusis, in basi paullo tumidis, saepe septatis, non ramosis, vel passim 

 e ramulis brevibus, saepe confertis, l-5-(saepe 3)-cellularibus, non 

 ramosis et non in pila productis, constans. Chromatophora pyrenoide 

 singulo. 



37 



