432 PERIODICITY OF THE PHYTOPLANKTON OF SOME BRITISH LAKES. 
Var. conrerta, W. & G. В. West. (PL 19. fig. 1.) 
Var. cellulis multo magis confertis, 
Long. colon. 73 y, lat. 52 ш: diam, cell, 156-2 p. 
Hab. Loch Katrine (March 1909), 
This variety differs only in the more crowded disposition of the cells, 
which are of approximately the same density as in A, delicatissima. 
T. APHANOTHECE NIDULANS, P. Richter, in. Wittr. & Nordst. Alg. Exsic. 
1584, по. 694. 
Var. ENboPHYTICA, W. & G. S. West. (Pl. 19. fig. 14.) 
Var. habitu endophytico intra colonias Cælospheæerii Nützingiani. 
Long. cell. 25-45 р; lat. cell, 08-1 д. 
Hab. Loch Lomond, Loch Katrine, Lough Neagh, ete., occurring as an 
endophyte within the colonies of Cirlospherium Kiitzingianum wherever that 
Alga attains a large maximum. 
The cells are of precisely the same form and size as many of the rod- 
shaped bacteria which frequent the gelatinous colonies of Algæ, but they are 
of a brilliant blue-green colour. 
[ We wish to emphasize the fact that the cells of this endophytie Aphanothece 
are not bacteria. This is the more necessary as rod-shaped bacteria occur 
commonly in and upon the colonies of Celosplierium and Gomphospheria, 
It is possible that the “ Bazillus sp. I” deseribed by Bachmann (Archiv 
für Hydrobiol. u. Planktonk. iii. 1907, p. 78, and p. 60, fig. iii 5) as occurring 
in the colonies of Gomphospheria Nägeliana is identical with Aphanothece 
nidulans var, endophytica, 
It would seem that the blue-green colour is the only outstanding feature 
which distinguishes species of Aphanothece from species of Bacillus, and ах 
all the above specimens were brilliantly coloured we have referred them to 
Aphanothecee—W. & G. К. West, 28th April, 1912. | 
EXPLANATION OF PLATE 19. 
Fig. 1. Aphanocapsa elachista, W. & G. S. West, var. conferta, var. п. x 500. 
2-9. Aphanocapsa delicatissima, sp. п. х 1000. 
4. Plectonema Вогуапит, Gomont. х 500. 
5-8. Spondylosium planum, (Wolle) nob. x 500. 
9-10. Ankistrodesmus tortilis, sp. п. x 1000. 
11-12. Roya cambrice, W. & G. S. West, forma limnetica. х 500. 
15. Tetraspora limnetica, sp. п. x 500. 
the cells. 
14. Aphanothece nidulans, P. Richter, var. endopAytica, var, n., within the colony 
of Celospherium  Kützingianum. — x 500, 
The pseudocilia are not shown on all 
