Aptogonum desmidium, Ralfs. Desm. (1848), p. 64, t. 32,
f. 1. Delponte Desm. (1876), p. 73, t. 3, f. 1-5. Brek Liste
Desm. (1856), p. 119.
var. a. Filament triangular, regularly twisted; crenatures
rounded.
Size. 18 x 28 g (D.) ; 17-25 p (R.).
Aptogonum desmidium, var. a. Ralfs. Desm. p. 64.
Desmidium aptogonum, var. /S. Archer in Prit. Inf. (1861),
p. 723.
Westmoreland, Wales ; Italy, Sweden.
Plate «, living cells; h, empty cells; c, transverse view.
var. ¡3. Filament plane, crenatures shallower and slightly
angular.
Desmidium aptogonum, ¡3. Ehrenbergii Rabh. FI. Alg. (1868),
p. 154. Lundell Desm. Suec. (1871), p. 95.
Odontella desmidium, Ehr. Inf. (1888), t. 16, f. 4.
Aptogonum desmidium, var ¡3. Ralfs. Desm. p. 64, t. 32, f. 1.
Desmidium aptogonum, var (3. Archer in Prit. Inf. (1861),
p. 728.
Aptogonum diagonum, Delponte Desm. (1876), t. 2, f. 6-10.
Westmoreland; France, Germany, Italy, United States.
S i z e . 8 2 x 1 8 (D.) ; 1 9 - 2 7 p (R.).
Plate V., fig. 1. d, living cells ; e, empty cells ; / , side view.
Sub.-secl. b. Cells free, not united in a filament.
Genus 7. DOC ID IUM . Brel. (1846).
Frond very elongated, straight, constricted a t th e mid d le ;
segments w ith an inflation a t th e base (rarely not so), often
w ith others above, or w ith whorls of knot-like projections;
ends abruptly truncate. Endocbrome with a terminal rounded
clear space a t each end, in which are active grannies.—
Archer in Pritch. Inf. 744.
D o c id ium n o d o sum . Bailey Micr. Ols., f . 4.
Frond stout, suture forming a r im ; segments th re e or
four times as long as broad, with four prominent inflated
nodes, including th e basal, wbicb is somewhat th e largest,
and which are due to so many whorls of knot-like prominences
or large tubercles ; ends entire, end view orenate.
S iz e . 0'3-0'395 mm. x 48-54 p; apex 30-39 p ; diam.
45-55 p in centre (W.).
Wolle Desm. U.S. (1884), p. 50, t. 11, f. 11, 12; t. 12, f.
20.
Docidium, nodosum, Bailey, var. Eihernicum, Archer Quart.
Micr. Journ. xii. (1872), p. 193. Rabh. Alg. Eur. (1868), p.
145. Ralfs. Desm. (1848), p. 218, t. 35, f. 8.
Pleurotcenium nodosum, Lundell Desm. Suec. (1871), p. 90.
Wood F. W a te r Alg® U.S. (1872), p. 120.
Closterium nodosum, Bailey in Amer. Journ. (1846), i., p.
127, f. 3.
H ab. In ponds.
Ireland, Sweden, United States.
Plate V II., fig. 2. a, living c e ll; I, empty cell.
D o c id ium c o ro n a tum . Brel, in Palfs. Desm. (1848), t. 36, fi. 6.
Frond stout, suture forming a thickened projecting rim ;
segments four to six times as long as broad, tapering, regularly
inflated upwards from th e base, so as to produce an
undulated margin, th e basal inflation th e most prominent,
the others less so, and wanting towards th e ends ; ends bordered
by prominent tubercles, projecting all round; end
view circular, bordered by th e tu b e rc le s; empty frond
coarsely punctate.
S iz e. Diam. 22-56 p (W.) ; 540x30-58 p (K.).
Archer in P rit. Inf. (1861), p. 745. Archer inMicr. Journ.
(1874), x iv , p. 214. Brebisson Liste Desm. (1856), p. 147-
Wolle Desm. U.S. (1884), 49, t. 11. f. 9, 10.
Pleurotaenium coronatum, Rabb. Alg. Eur. (1868), p. 143.
Kiroh. Alg. Schles. (1878), p. 144.
Ireland, France, United States.
Plate V I., fig. 1. a, living cell; h, empty cell; c, transverse view.
D o c id ium n oB ile . (Piohter.) Lnndell Desm. Suec. (19UV), p.9,%.
Elongated, subcylindrioal, even, ten to twelve times as
long as broad, a little or indistinctly constricted in the
centre ; segments a little attenuated towards th e truncate
apices, with about eight undulations.
S iz e. 0'21-0’26 mm. x 20-35 p (Ri.) ; 0'175 mm. x 14 /a
(L.).
Pleurotcenium (Docidium) nobile, Richter in Hedwigia
(1865), iv., p. 129. Archer in Micr. Journ. xii. (1872), p.
86. Rabh. Alg. Eur. (1868), p. 142.
H ab. Amongst Sphagnum.
Ireland, Sweden, Germany.
Plate V II., fig. 3. a, living cell; I, empty cell; c, end |of empty cell
further magnified.