114 MR. G. S. WEST ON THE FRESHWATER ALGE 
lacks the small tumours which occur within the lateral lobules of FEuastrum 
truncatiforme. The large scrobiculation in the centre of the semicells of 
E. truncatum is likewise absent from Æ. truncatiforme. 
Compare also with Æ. pseudopectinatum, Schmidle, var. evolutum, Schmidle 
(in Engl. Bot. Jahrb. xxxii. (1903) p. 72, t. 2. fig. 6). 
Genus MICRASTERIAS, Ag. 
62. MICRASTERIAS INCISA, Breb., ex Ralfs, Brit. Desm. (1848) p. 211; 
W. B. Turn. т К. Sv. Vet.-Akad. Handl. xxv. (1893) no. 5, p. 89 (a. typica). 
—Euastrum incisum, Breb. in Menegh. Synops. Desm. (1840) p. 216. 
Holocystis incisa, ©. C. Wall. in Ann. Маа. Nat. Hist. ser. 3, v. (1860) 
p. 276, t. 13. figs. 4, 5. 
Forma lobis lateralibus oblique truncatis; spinis totis minoribus. 
Long. 56 р; lat. cum spin. 60 ш; lat. isthm. 11 р. 
Nyasa.—In swamp, Kota Kota (20 June, 1904; no. 18). 
Tanganyika.—In swamp, Kituta (26 Aug. 1904; по. 80). 
63. MICRASTERIAS CUNNINGTONH, sp. п. (Pl. 7. figs. 1-2.) 
M. mediocris, circiter 14-plo longior quam latior, elliptica, profundissime 
constricta, sinu angusto sed leviter aperto ; semicellulie quinquelobe, in- 
cisuris inter lobos non profundis et apertis; lobo polari late et breviter 
euneato (late campanulato e basi subangusto), apice convexo sed late 
emarginato ad medium, cum dentibus irregularibus circ. 10 ad marginem 
superiorem et angulis lateralibus unidentatis; lobis lateralibus subeequalibus 
(superioribus majoribus), cum incisura primaria mediana et incisuris parvis 
secundis duobus, lobulis emarginato-bispinatis (raro trispinatis) quattuor ; 
membrana irregulariter et subsparse denticulato-spinata. Semicellule a 
latere vise ovato-lanceolate, ad basin subrotundate, lateribus subretusis, 
apice rotundato et tridentato, marginibus lateralibus dense denticulato- 
spinatis. 
Long. 192 p ; lat. 138 u ; lat. max. lob. polar. 74-78 ш; lat. isthm. 28 ш; 
crass. sine spin. 54-56 p. 
Victoria Nyanza.—In swampy pools near the shore, Bukoba (20 Apr. 
1905 ; no. 251). 
This species can best be compared with M. apiculata, (Ehrenb.) Menegh., 
from which it is at once distinguished by the shallow incisions and the much 
wider and shorter polar lobe. The spines are also shorter, and they are 
much more irregular in size and disposition than those of М. apiculata, 
especially towards the centre of the semicells. It is, however, the polar 
lobe which is the distinctive feature of M. Cunningtonii. It is very widely 
campanulate from a rather narrow base, and the disposition of the spines on 
its convex-emarginate apex is also peculiar. 
