New British Freshwater Algse. By W. and G. 8. West. 163 
Class MyxoPHYCEiE. 
Sub-class Hormogonej:. 
Heterocysteae. 
Order Kivulariaoe^:. 
Genus Calothrix Ag. 
40. C. parietina (Nag.) Thur. (Born, et Flah., Bevis. des 
Nostoch. Heterocyst., p. 366). 
Crass, fil. 7*7-13 /x; crass, tricb. 4-7*5 /i. 
Eab. Slieve Donard, Co. Dowd, Ireland. 
Order Scytonemace^e. 
Genus Scytonema Ag. 
41. S. ambiguum Ivutz. (Species Algarum, p. 894 ; Tabulae 
phycolog., ii. p. 7, t. 26, f. ii. ; West, Alg. from W. Indies, 
JourD. Linn. Soc. Bot., xxx. (1894) p. 270, pi. xv. figs. 
11-15). 
Crass, fil. 8-10*5 /a; crass, tricb. 2 *4-2 *8 /a. 
Hob. Near Westport, Co. Galway, Ireland. 
This is new to the British Isles, and was associated with Stiyo- 
nema hormoides and Mesoteenium chlamydosporum Arch. 
Order Sirosiphoniace^e. 
Genus Eapalosiphon Nag. 
42. H. eibernicus sp. n. 
H. inter alias algas aquaticas repertus, aeruginosus, filis 
primariis subflexuosis, vaginis adultis arctissimis (interdum 
indistinctis), e cellulis singulis (vel binis hinc inde) formatis, 
cellulis rotundo-quadratis vel diametro brevioribus, dense 
unilateraliter ramosis ; ramis erectis elongatis flexuosis, filo 
primario paullo angustioribus vel aequalibus, vaginis arctis et 
distinctis, cellulis diametro 3-4-plo (usque ad 8-pio) longiori- 
bus ; heterocystis intercalaribus diametro 14-5-plo longioribus. 
Crass, fil. prim. 7 *2-9 *5 /a; crass, ram. 4 *5-5; 5 /a; 
eras, heterocyst. 5 /a. 
Hab. Glen Caragh, Co. Kerry, Ireland. 
This species comes nearest to E. intricatus West (Freshw. 
Alg. from W. Indies, Journ. Linn. Soc., xxx. (1894) p. 271, pi. xv. 
figs. 16-28), but it has a different habit, and the filaments are not 
densely intricate. Moreover, the primary filaments and branches 
are rather different, the former having rounded cells as long as broad 
(or shorter), and the latter cylindrical cells from three times as long 
as broad to — in rare cases — even eight times. The primary filaments 
are rather short and the branches very dense, whereas in E. intricatus 
