286 
Transactions of the Society, 
P. digitus Breb. S., D., R, Do., B., F. 
P. interruftum Breb. Do. 
P. closterioides Ealfs. A., Do. 
This species sometimes has one or two bands, which show as 
distinct papillae on the margin of the central part of the cell. 
A small form was also seen ; long. 98 jx, lat. 22 yu. 
P. navicula Breb. Do., F. 
P. Brebissonii Ealfs. Common. 
P. oblongum De Bary. S. 
P. truncatum Breb. F., B., Twll Du. 
P. Mooreanum Arch. B. 
P. minutissimum Nord. C., F. 
P. cucurbitinum Bisset. S. 
Genus Cylindrocystis Meneg. 
C. diflos'pora Lund. F., C., B., Llyn Idwal. 
C. crassa De Bary. C., B., F., D. 
Genus Tetmemorus Ealfs. 
T. Brebissonii Ealfs. Common, 
var. jB turgidus Ealfs. S. 
var. 7 (De Bary) Arch. Twll Du. 
T. granulatus Ealfs. Common. 
T. Idsvis Ealfs. S., Do., D., F., Twll Du. 
Genus Spirotsenia Breb. 
S. condensata Breb. F., P., Do., D. 
S. truncata Arch. C. 
Long. 50 fx; lat. 12*5 fx. 
Genus Micrasterias Ag. 
M. mucronata (Dixon) Eabh. D., S. 
M. americana (Ehrb.) Ealfs. S. 
var. recta Wolle. Do. 
var. Lewisiana nov. var. Fig. 13. 
Yar. lobis polaribus subintegris et latioribus, incisuris 
angustioribus infra lobos polares. 
This has the end lobes subentire and wider, the infra-apical 
incisions are narrower also than in the var. recta Wolle, which it 
approaches. P. 
This is a very distinct variety, and very distant from “forma 
major Eeinsch,” with which it is worth comparing, as this latter 
seems to be at the other extreme. 
M, denticulata Breb. D., S., P., Do., B. 
M. rotata (Grev.) Ealfs. P., Do. 
