OF THE THIRD TANGANYIKA EXPEDITION. 197 
duplo longioribus, polis subrotundatis; cytoplasmate lete seruginoso et 
granuloso (fere ut in Chroococco turgido). 
Long. cell. 5:5-10 ш; lat. cell. 4:5—5:5 р; crass. vag. 11-19 ш (usque 
ad 27 u). 
Tanganyika.—Epiphytic оп Chetomorpha Linum, floating in Kituta Bay 
(26 Aug. 1904 ; no. 79). 
This plant belongs unquestionably to the Chroococcacese, the cells having 
very much the same structure as those of Chroococcus. И would fall naturally 
into Hansgirg’s genus Chroodactylon (Ber. Deutsch. Bot. Ges, i. (1885) t. 3), 
but for the fact that Hansgirg has since placed both Asterocystis, Gobi (1879), 
and his own genus Chroodactylon (1885) as sections of “ Allogonium, Kiitz.” 
(vide Hedwigia (1887), Heft 1). Although Hansgirg was in error in 
reviving * Allogonium," a name given by Kützing to a number of Algz of 
widely different affinities and all of which are now placed in other genera, 
yet he was evidently of the opinion that Asterocystis and Chroodactylon were 
scarcely distinct. It is for this reason that I have placed the African plant 
as a species of the former genus. Schmitz (in Engl. Natür. Pflanzenfam. 
1 Teil, Abt. 2, p. 314) places Asterocystis in the Bangiacee, but the species 
observed from Tanganyika is a typical Blue-green Alga. 
The colonies of Asterocystis africana reach a diameter across the spreading 
branches of about 360 p. The gelatinous sheath at the base of the primary 
filament is somewhat expanded and is firmly attached to the wall of the 
Chetomorpha, in which it makes a pit-like depression often 14 р in depth. 
NAVICULACEZ. 
319. NAvICULA sERIANS, Вт. in Kütz. Bacill. (1844) p. 92, t. 30. fig. 23 ; 
W. Sm. Brit. Diat. t. 16. fig. 130. 
Nyasa.—In scrapings from bottom of s.s. ‘Guendolen’ at 5. end of lake 
(15 June, 1904; no. 577). 
GOMPHONEMACEX. 
380. RHOICOSPHENIA CURVATA, (Kütz.) Grun. in Abh. zool.-bot. Ges. Wien, 
x. (1860) p. 511; Van Heurck, Synops. Diat. Belg. t. 26. figs. 1, 2, 3. 
Tanganyika.—On the bottom of Dr. Cunnington's dau (24 Jan. 1905; 
no. 217). 
The University, Birmingham, 
19th March, 1907. 
LINN. JOURN,—BOTANY, VOL. XXXVIII, P 
