10 
Transactions of the Society. 
Euastrum oblongum Grev. 
„ afBne Rifs. 
„ didelta Rifs. 
„ ansatum Rifs. 
„ circulare Hass. 
„ sinuosum Len. 
„ pectinatum Breb. 
,. gemmatum Ktz. 
„ elegans Breb. 
* Euastrum inerme Lund. 
No British locality has yet been given for this little desmid, 
■which seems to me sufficiently distinct from E. elegans. Punchbowl. 
Euastrum binale Rifs. 
Cosmarium cucumis Cord. 
„ Ralfsii Breb. 
„ pachydermum Lund. 
„ pyramidatum Breb. 
„ pseudo-pyramidatum Lund. 
„ pseudo-nitidulum Nordst. 
Cosmarium minutum sp. n. (Fig. 11.) 
Very minute. Length and breadth about 15-18 ^ ; semi-cells 
hexagonal ; ends quite straight and parallel, each side representing a 
nearly equilateral triangle ; incision narrow and deep ; a large con- 
spicuous pyrenoid in the middle of each semi-cell. This minute 
species was seen frequently in bog-pools. It agrees nearly with 
C. truncatellum (Pert.) Rbh., except in the number of pyrenoids, an 
important difference ; also with C. minutissimum Heim. (Abh. Zool.- 
Bot. Gesell. Wien, 1891, p. 600, t. v. f. 14, non Arch.), but wants the 
tooth-like projections at the angles described in that species. It dif- 
fers from C. Schliephackianum Grun. in the angles being sharp and 
not rounded ; and from C. perpusillum West MS., from Ireland, in 
the sides being quite straight, and not undulate, and in its some- 
what larger size. 
Cosmarium Meneghinii Breb. 
This minute species was very common in bog-pools. 
Cosmarium bioculatum Breb. 
,, tetraophthalmum Breb. 
„ Brebissonii Men. 
„ margaritiferum Men. 
„ punctulatum Breb. 
„ botrytis Men. 
*Cosmarium Ungerianum (Nag.) Arch. (Pigs. 12, 13.) 
Medium size. Outline a nearly equilateral hexagon. Length 
