22 Hungary. Italy. Norway. Sweden. Denmark. S. Russia. Faeroes

22
BRITISH DESMIDIAOEJI.
Hungary.
Italy.
Norway.
Sweden.
Denmark.
S. Russia.
Faeroes.
Kordofan.
Central China.
Japan. India. Burma. Ceylon. Australia. Mada­
gascar. Central Africa. United States. Jamaica.
Porto Rico. Brazil. Ecuador. Bolivia.
Roy states that " one form of this species has a distinct
isthmus, connecting the semicells; its zygospore (found in a
small pool north of Loch Dawin, Aberdeen) is globular,
smooth, and twice the size of a semicell." Perhaps this
statement refers to forma panditriformis Heimerl, a form
which we find fairly generally distributed.
Forma punctata Lagerh.
(PI. L X V I I , fig. 4.)
C. monUiforme /3 punctatum Lagerh. Algol. Biclr. II, 1887, p. 197; West
& G. S. West, Alg. Madag. 1S95, p. 70, t. 9, f. 31.
Cell-wall punctate, often becoming yellow.
Length 24-43 / A ; breadth 1 4 - 2 5 / A ; breadth of
isthmus S'b-6'7 / A .
WALES.—Moel Siabod, Carnarvonshire !
Geor/r. Distribution.—Madagascar.
Porto Rico.
Forma panduriformis Heimerl. (PI. L X V I I , figs. 8-9.)
0. monUiforme forma panduriformis Heimerl, Desm. alp. 1891, p. 598,
t. 5, f. 11; West in Naturalist, 1893, p. 214; Schmidle, Beitr. alp. Alg.
1895, p. 387; West & G. S. West, Alg. S. England, 1897, p. 491; Some
Desm. U.S. 1898, p. 310; Alga-fl. Yorks. 1900, p. 86; Alg. N. Ireland,
1902, p. 41; Further Contrib. Plankton Scott. Lochs, 1905, p. 484.
Dysphinctium inferum Turn. Freshw. Alg. E. India, 1893, p. 40, t. 1, f. 21.
? Pleuroteeniopsis Volkensii Hieron. Conj. in Engl. Pflanzenw. Oat-Africa,
1895, p. 20. [Consult Schmidle, Ost-Afrika Desmid. 1898, p. 25.]
Cells with a broader isthmus and an obtusely
rounded sinus; cell-wall smooth.
Length 17 5-25 /A ; breadth 10-15 JU, ; breadth of
isthmus 6-10 \x.
ENGLAND.—Brothers' Water and Helvellyn, West­
moreland ! Pilmoor, N. Yorks ! Riccall Common, E.
Y o r k s ! Thursley Common, Surrey! New Forest,
Hants ! Withiel, Cornwall!
WALES.—Capel Curig, Carnarvonshire ! Not un­
common in the plankton of the Carnarvonshire lakes !
SCOTLAND.—Rhiconich, Sutherland ! Moidart, and
,