26 COCCOPHYCE. 
Nephrocytium Agardhianum. Wig, Einz. Alg. p. 80. 
Cells pale green, almost homogenous, 4-6 times as long 
as broad, spirally arranged, in families of 4-8 cells; tegu- 
ment thin which encloses them, length 2-3 times the breadth. 
Size. Cells diam. ‘0038--0075 mm. (Rabh.). mx 
Rabh. Alg. iii. 52. Nag. Einz. Alg. (forma minor), t. 11. 
C.a-h. Kirch. Alg. Schl. p. 112. 
In ditches, bogs, &c. 
Plate XT. fig. 1. a, 6, families; c,end view; d, free cells. All 
magnified 400 diam. 
Nephrocytium Naegelii. Grun. Rabh, Alg. 111. 52. 
Cells dark green, granular, twice as long as broad, irre- 
gularly disposed, families usually composed of 16 cells ; tegu- 
ment thick. 
Size. Cells diam. -011--022 mm. (Rabh.). 
Nephrocytium Agardhianum, majus Nag. Hinz. Alg. t. iii. C. 
fig.i, k,p. Kirch. Alg. Schl. p. 118. 
In similar or the same places as the foregoing, with which 
it is often associated. 
Plate XT. fig. 2. a,b, c, family groups; d, free cells. All magnified 
400 diam. 
Genus 19. OOCYSTIS. Wiig. (1855.) 
Cells oblong, chlorophyllous, either solitary or binate, qua- 
ternate, or octonate; contained at first within an ample simple 
mother cell, at length free by dissolution of the membrane. 
This genus, as Mr. Archer has observed (Micr. Journ., 1877, p. 105), 
comes very near Nephrocytium, the seemingly only very tangible dis- 
tinction (it is a very constant one at the least), being the reniform (not 
elliptical) cells in the latter genus; but as forms merely, of more or 
less frequent occurrence, those referred to both the genera are indeed 
very distinct and constant. 
Oocystis gigas. Archer, Quart. Journ. Micr. Sci., 1877, p. 105. 
Mother-cell broadly elliptic, almost subglobose, large ; family 
usually consisting of two cells, 
Size. Mother-cell :06--07 x °05--06 mm. 
In pools. Ireland. 
The broadly elliptical cells are very large, and are really subspheerical. 
“The cell wall,” Mr. Archer says, “is by comparison very thick, with 
the somewhat nodular little thickening at each pole; the chlorophyll 
granules, in examples in which these were not too dense, could be seen 
arranged parietally in « beautifully and curiously regular reticulate 
manner, the ‘meshes or interspaces of the interior surface of the wall 
being bare of them. He had only seen two young cells within theex- 
panded mother-cell, four, eight, to sixteen being common in Oocystis 
Naegelii. In examples about to produce young individuals, the contents 
