26 COCCOPHYCE.E. 



Nephrocytium Agardhiaivum. Nag. 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. -003S--0075 mm. (Rdbli.). 



Rabh. Alg. iii. 52. Nag. Einz. Alg. (forma minor'), t. iii. 

 C. a-h. Kirch. Alg. Schl. p. 112. 



In ditches, bogs, &c. 



Plate XI. Jig. 1. , b, families ; c, end view ; d, free cells. All 

 magnified 400 diam. 



Nephrocytium Naegelii. Grun. Rabh. Alg. in. 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.}. 



Nephrocytiwn Agardhiamim, ma/jus Nag. Einz. Alg. t. iii. C. 

 fig. i, k, p. Kirch. Alg. Schl. p. 113. 



In similar or the same places as the foregoing, with which 

 it is often associated. 



Plate XI. Jig. 2. a, b, c, family groups ; d, free cells. All magnified 

 400 diam. 



GENUS 19. OOCYSTZS. Nag. (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 ~Nep~]irocytium t 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 subsphaerical. 

 " 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 a 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 



