136 MR. С. $. WEST ON THE FRESHWATER ALGJE 
Nyasa.—Plankton, Anchorage Day (14 June, 1904; no. 10). 
Tanganyika.—In swamp, Kituta (26 Aug. 1904; по. 80). In swamp, 
Mbete (28 Sept. 1904 ; no. 108). 
Victoria Nyanza.—Near Entebbe (1 May, 1905 : no. 620). 
This species was abundant in some of the collections, and the cells showed 
great variation in the form of the external margin. It is a very characteristic 
plant and should not be confused with any other species of the genus. 
Lemaire's * var. quinqueradiatum " is one of its commonest forms. 
Var. INTERMEDIUM, (Bohlin) nob.—C. pulchrum, Schmidle, var. intermedium, 
Bohlin, in Bih. К. Sv. Vet.-Akad. Нап. xxii. (1897) no. 7, p. 35, t. 2. 
figs. 16, 17. С. cruciatum, Schmidle, in Bot. Centralbl, |xxxi. (1900) no. 15, 
Diam. coenob. usque ad 108 ш; diam. cell. 18-16 д. 
Nyasa.— Plankton, Anchorage Вау (14 June, 1904 ; по. 10). 
The cells of this variety, as in the case of the type, possess from four to 
six short radiating processes. The variety only differs in the bluntness of the 
outstanding projections, which are rounded and not truncate. 
Var. NAsUTUM, (Schmidle) nob.—C. pulchrum, var. nasutum, Schmidle, in 
Engl. Bot. Jahrb. xxvi. (1898) p. 6 ; xxxii. (1903) p. 85, t. 3. fig. 7. 
Diam. сепоЬ. 40-114 ш; diam. cell. 8-27 ш; long. process. margin. 
45-65 д. 
Victoria Nyanza.—Plankton, near Bukoba (18 Apr. 1905 ; no. 249). 
This well-marked variety occurred abundantly, and a large number of auto- 
colonies were observed in process of formation in the mother-cells. The 
principal feature of the variety could be recognized when the auto-colonies 
were only 18 win diameter. The marginal processes were sometimes truncate 
and sometimes broadly rounded. It was originally described from the 
plankton of Victoria Nyanza by Schmidle in 1898. 
152. ÜŒLASTRUM COMPOSITUM, sp. п. (PI. 5. figs. 8-9.) - 
C. ccemnobiis cubicis e subfamiliis 8 formatis vel sphericis e subfamiliis 
pluribus formatis ; subfamilia unaquaque fetraédrica cum angulis abrupte 
truncatis vel depresso-pyramidatis, e cellulis parvis 4 tetraédrica dispositis 
compositis, et cum lacuna minuta inter cellulas ; lacunis magnis inter sub- 
familias, lis coonobiorum cubicorum irregulariter rotundo-rectangularibus, 
iis coenobiorum sphericorum subtriangularibus. Membrana cellularum firma 
glabra et non incrassata. 
Diam. ecnob. 36-82 и; diam. cell. 6-10 д. 
Victoria Nyanza.—Plankton, near Bukoba (21 Apr. 1905; no. 252), 
Among Utricularia, near Entebbe (1 Мау, 1905 ; no. 620). 
This interesting Colastrum differs from all other species of the genus in 
having a tetrahedral group of four cells in place of what would normally be 
a single cell. The interstices between the groups are very large, and there is 
