20 COCCOPHYCES. 
Rhaphidium duplex. Kutz. Phyc. Germ. p. 144. 
Fusiform, slender, slightly sigmoid, single, or 2, 3, or 4 
laterally connected at the poles, otherwise free. 
Rhaphidium triplex, Rabh. Krypt. Fl. Sax., p. 134. 
Scenedesmus duplex, Ralfs Desm. 193, t. 34, f. 17. 
Rhaphidium polymorphum var. d. sigmoideum, Rabh. Aly. iii. 
p. 45. 
In pools (apparently rare). 
“ Cells linear-lanceolate; extremities tapering to a fine point and 
curved in opposite directions. The cells closely united, frequently the 
frond, consists of only a single pair of cells so connected, but sometimes 
of two or even three of these pairs, which, however, are remote from 
each other, in this case; as the connecting mucous is colourless, they 
look like distinct plants, and their relation can be detected only by 
moving the frond. If kept in water for a few days, the cells separate 
from each other.’—Ralfs. 
This description is scarcely accurate, as each cell is a distinct plant. 
Plate VIIT. fig. 5. a, cells magnified 400 ; 6, magnified 800 diam. 
Genus 14. DICTYOSPHZERIUM. Wiig. (1849.) 
Cells elliptic, with thick confluent mucous investment, com- 
bined in numbers into free-swimming one-layered hollow- 
globular families, one always at the ends of delicate threads 
which proceed from the central point of the family, and which 
become repeatedly branched towards the periphery ; division at 
the commencement of a series of generations in all directions of 
space ; afterwards, as regards the middle point of the aggre- 
gate family, as a rule, alternating only in the two tangental 
directions. 
‘ ay three described species, all of which have occurred in the British 
sles. 
Dictyospherium Ehrenbergianum. Nig. Einz. Alg.p. 73. 
Families aggregated in a globular, or broadly elliptical 
figure; cells elliptic, very minute, about one-third as broad as 
long. 
Size. Cells -004--0075 mm. (Rabh.), ‘004-007 mm (Kirch.). 
Rabh. Alg. iii. 47. Kirch. Alg. Schl. p. 106. 
Amongst Conferve. 
“This form is very minute, and in suitable places, common, the 
families in the aggregate forming a globular, or broadly elliptic, or 
sometimes subcubical figure; the rate of growth of the delicate thread 
being equal all round, the cells at the ends of each of its dichotomous 
ramifications stand at nearly equal distance from the original centre ; 
hence the regular figure of the aggregate family. The individual cells 
are elliptic, and very minute.”—Archer. 
Plate IX. fig. 1. Families magnified 400 diam.; 6, fragment with 
cells X 400 diam. ; ¢, variety with spherical cells, 
