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P ed ia strum Boryanum. Turp. Baih. Alg. n i . 74.
Cænobium orbicular, oblong, or elliptic, variable in size, con-
tinnous, bright green, composed of 4-8-16-32-64 (rarely 128)
cells. Cells of periphery more or less deeply emarginate, or
tvro-lobed, lobes born-like, horns colourless, short or long,
straight, obtuse or nearly so, sometimes a little thickened ;
central cells very closely concrete, 4-6 angled, angular or tru n cate
in front, or slightly repand ; membrane decussately punctate.
S i z e . Cells •02-'002 mm. transverse diam.
Braun Unie. Alg. p. 86. Ralfs Ann. Nat. Hist. xiv. (1844)
t. 12, f. 7, lower. Ralfs Desm. t. 31, f. 9 a. Hassall Alg. t.
86, f. 13.
Pediastrum hexactis, Hassall Alg. t. 92, f. 5.
Pediastrum Napoleonis, Ralfs Desm. t. 31, f. 7 a and d (short-
horned form) ; f. b (long-horned form).
Pediastrum simplex B . cruciatum, Ralfs Desm. t. 34, f. 15 d.
Pediastrum granulatum, Braun “ Rejuvenescence,” pi. 3 ,4
(English edition). Pritch. Infus. t. 1, f. 59-69.
In boggy pools.
Plate X7I. fig. 11. a, 4-oelled cænobium; b and e, IB-celled coeno-
bium; c, 32-celled ooenobium ; d, 8-celled ooenobium X 400 diameters.
var. B. gran u la tum , Kntz.
Cells as in the preceding, but all the cells and the horns distinctly
granulated.
Braun Unicel. Alg. p. 90.
Pediastrum granulatum, Ralfs Desm. t. 31, f. 8.
In the same localities.
Plate XVI. fig. 12. a, b, 8-oelled coenobia X 400 diameters.
Pedia strum b id en tu lum . Br. Unie. Alg. p. 91.
Cænobium orbicular or oblong, continuous, deep green,
sometimes bluish green, nearly blue, composed of 16-32 cells;
cells of periphery two-lobed to the middle, lobes straight, produced
into a truncate, bidentate horn ; central cells 4-5 angled,
slightly repand in front.
Rabh. Alg. iii. 77.
Pediastrum ellipticum, var. ¡3 ., Ralfs. Desm. t. 31, f. 10 a ,b , c.
In boggy pools.
Distinguished by the marginal cells being divided into two obtuse
lobes, resembling blunt borns, each of whicb is two-toothed.
Plate X V I I. fig. 1. a, part of a 32-celled ccenobiumj 5, larger 32-
celled cænobium, after Balfs, X 400 diameters ; c, 16-celled cænobium ;
d, marginal cell.
P ed ia strum con stx ic tum . Hass. t. 86, /. 15, 16.
Cænobium orbicular, or nearly orbicular, bright green, con-
tinuous, smooth (?), composed of 16-32 cells ; cells of the
periphery irregularly two-lobed, sinus narrow, lobes unequal, now
and then constricted at the base, produced into an obtuse, ra ther
thick horn ; central cells polygonal, repand in front.
Rabh. Alg. iii. 77.
Pediastrum ellipticum, Ralfs Desm. t. 31, f. 10 d.
Pediastrum Boryanum, ji., Ralfs Ann. Nat. Hist. xiv. (1844)
f. 8.
In standing water.
Braun suspects the verity of this species, which we have never seen.
Plate X V II. fig. 2. a, 32-oelled cænobium ; b, 16-celled ooeuobium X
400 diameters, after Ealfs ; c, marginal cells.
P e d ia s trum g r a c ile . Br. Unie. Alg. p. 93.
Cells quaternate, closely joined in a circle, centre open,
rarely closed ; cells deeply two-lobed, lobes ovate, produced
into a long divergent, acuminate horn.
Rabh. Alg. iii. 75.
Pediastrum simplex, Ralfs Desm. t. 34, f. 15 a 5.
In pools.
This appears to be a very rare species, at first referred to P. simplex
Meyen, from which it differs in the cells, being deeply two-lobed.
Plate XVII. fig. 3. 4-oelled coenobia X 400 diameters, after Ealfs.
P e d ia s trum p e r tu s um . Kutz. Phy. Oerm. p. 143.
Cænobium orbicular, pierced with laounæ, of variable size,
composed of as many as 64 cells ; cells of the periphery loosely
connected at the base, bilobed almost to the middle ; lobes
straight, produced into a hyaline horn, sometimes acute, sometimes
obtuse or truncate ; central cells more or less exactly
quadrangular, emarginate in front, even, with two paler spots.
S i z e . Perfect cells •016-'022 mm. transverse diam.
Rabh. Alg. iii. 75. Ralfs Desm. t. 31, f. 6 a, b. Braun
Unicell. Alg. p. 92.
Pediastrum Napoleonis, Ralfs Desm. t. 81, f. 7 c and e.
Pediastrum selenæa, Kutz., Pritch. Inf. t. 1, f. 53.
In pools.
Plate X V II. fig. 4. a, b, c, 8-oelled coenobia ; d, 32-celled cænobinm ;
e, IC-oelled cænobium.
var. b. c l a th r a tu m . Br. Unicell. Alg. p . 93.
Disc pierced with larger openings ; central cells deeply
notched and bilobate.
Pediastrum cribriforme, Hassall Alg. t. 92, f. 4.
Plate XVII. fig. 5. 16-celled oæiiohinm.
var. c. b ia c h y lo h um . Brawn Unicell. Alg.p. 93.
Cells larger, those of the periphery emarginate or triangularly
notched, shortly two-lobed ; horns very short, truncate.