42 COCCOPHYCER. 
Pediastrum Boryanum. Turp. Rabh. Alg. 111. 74. 
Ceenobium orbicular, oblong, or elliptic, variable in size, con- 
tinuous, bright green, composed of 4-8-16-32-64 (rarely 128) 
cells. Cells of periphery more or less deeply emarginate, or 
two-lobed, lobes horn-like, horns colourless, short or Jong, 
straight, obtuse or nearly so, sometimes a little thickened ; 
central cells very closely concrete, 4-6 angled, angular or trun- 
cate in front, or slightly repand ; membrane decussately punc- 
tate. 
Size. 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. 9a. Hassall Alg. t. 
86, f. 13. 
Pediastrum heractis, Hassall Alg. t. 92, f. 5. 
Pediastrum Napoleonis, Ralfs Desm. t. 31, f. 7 a and d (short- 
horned form) ; f. 6 (long-horned form). 
Pediastrum simplex B. cruciatum, Ralfs Desm. t. 34, f. 15 d. 
Pediastrum granulatum, Braun “ Rejuvenescence,” pl. 3, 4 
(English edition). Pritch. Infus. t. 1, f. 59-69. 
In boggy pools. 
Plate XVI. fig. 11. a, 4-celled ccenobium; 8 and e, 16-celled coeno. 
bium; ¢, 32-celled ccenobium ; d, 8-celled coonobium X 400 diameters. 
var. B. granulatum. Xutz. 
Cells as in the preceding, but all the cells and the horns dis- 
tinctly granulated. 
Braun Unicel. Alg. p. 90. 
Pediastrum granulatum, Ralfs Desm. t. 31, f. 8. 
In the same localities. 
Plate XVI. fig. 12. a, 5, 8-celled ccenobia X 400 diameters. 
Pediastrum bidentulum. Br. Unic. Alg. p. 91. 
Cenobium orbicular or oblong, continuous, deep green, 
sometimes bluish green, nearly blue, composed of 16-82 cells; 
cells of periphery two-lobed to the middle, lobes straight, pro- 
duced into a truncate, bidentate horn; central cells 4-5 angled, 
slightly repand in front. 
Rabh. Alg. ili. 77. 
Pediastrum ellipticum, var. B., Ralfs. Desm. t. 31, f. 10 a, }, ¢. 
In boggy pools. 
Distinguished by the marginal cells being divided into two obtuse 
lobes, resembling blunt horns, each of which is two-toothed. 
Plate XVII. fig. 1. a. part of a 32-celled ccenobium; 3, larger 32- 
celled ccenobium, after Ralfs, x 400 diameters; c, 16-celled ccenobium ;, 
d, marginal cell. , 
Pediastrum constrictum. Hass. t. 86, f. 15, 16. 
. Ceenobium orbicular, or nearly orbicular, bright green, con- 
tinuous, smooth (?), composed of 16-32 cells; cells of the 
