516 Annals of the South African Museum. 



( Pig. LO, I> ) (up to twice as long as broad). The chloroplast appeared 

 as a broad, girdle-shaped band, covering more than half the circum- 

 ference of the cell, and, in many cases al least, contained two pyrenoids. 

 The cell-wall always appeared to be more or less mucilaginous (in 

 some cases so markedly so that the longitudinal edges of the filaments 

 were ill-defined, cf. Fig. 10, B and B). There was sometimes a very 

 faint constriction between the cells. In most of these respects there 

 is agreement with the diagnosis in Heering (op. cit.): Wille (Bidr. 

 t. Sydamerikas Algflora, I-III, Bih. K. Sv. Vet.-Akad. Handl., viii, 

 No. 18, 1884, Tab. Ill, figs. 96-98) also figures this species with cells 

 of very variable length, faint constriction, and gelatinous walls. 

 Moreover, the habitat is a likely one for the species. 



At rare intervals the filaments widened out considerably, and here 

 consisted of more than a single row of cells. At these points rather 

 irregular division appeared to have taken place, as the cells were not 

 arranged in an orderly manner. The w r alls were always strongly 

 mucilaginous at such places. 



In quite a considerable number of the filaments akinete-formation 

 was taking place. These aki notes were either produced singly (Fig. 

 10, A, B), or in chains ( Fig. 10, 0), often of some length. The single 

 akinetes were always absolutely spherical ; those produced in chains 

 were often a little flattened wdiere in contact with one another, or 

 showed an oval shape, being elongated either in the transverse or the 

 longitudinal direction. Each akinete was provided with a firm, thick 

 membrane, and had opaque, more or less homogeneous contents. The 

 diameter of these akinetes (without the surrounding mucilage-sheath) 

 was on the average 12 /j.. Many of them appeared to have undergone 

 division into two (Fig. 10, B). 



In a number of the filaments obvious splitting into short lengths 

 of several cells was taking place (Fig. 10, D). Altogether, although 

 there were some very long filaments, the majority were of no very 

 considerable length. 



4. Ulothrix gelabinosa, n. sp. (Fig. 11.) 



Filis vegetativis juvenalibus 10-15 jx latis, inter cellulas saepe 

 leviter constrictis, cellulis 3 4 plo longioribus quam latis, memlirana 

 incrassata non laniellata, F5-3ju crassa; filis vegetativis senioribus 

 25-37 /jl latis, inter cellulas interdum constrictis, cellulis tarn longis 

 quam latis vel dimidio latioribus, membrana valde incrassata gela- 

 tinosa non laniellata, 5-9 ^ crassa. Chromatophora in cellulis, 

 junioribus in media cellula modo ciuguli, marginibus integris ; in 

 cellulis senioribus tota cellula plena est chromatophora, quae est 



