PALMELLACEZ. 27 
became more dense, and the reticulated arrangements lost, or rather, 
perhaps, more properly speaking, the interspaces become clothed with 
chlorophy!] granules, At first glance this might be mistaken, under a 
low power, for that small form of Eremosphera viridis, which origi- 
nates when the individuals of the ordinary large form produce simul- 
taneously four, in place of two danghter cells; but the evident elliptic 
figure and the thickened poles, as well as the different arrangement of 
the chlorophyll contents, would, on closer inspection, at once distinguish 
them. Mr. Archer has drawn attention to the seemingly curious very 
great expansion of the wall of the mother-cell, almost looking as if in 
anticipation, rather than as in consequence of the growth of a young 
‘prood’ of two, four, eight, or sixteen daughter-cells, so much s0 that 
it almost had the aspect of a fresh growth, rather than that of a mere 
swelling up of the old membrane.”— Quart, Journ. Micr. Sci, 1877, 
p. 105. 
Oocystis setigera. Archer, in Quart. Journ, Micr. Sci., 1877, p.194. 
We are unable to give any description of this species which, 
as far as we are aware, bears only a manuscript name, Neither 
are we able to give figures of either species, although we hope 
to do so hereafter. 
GENUS 20. DIMORPHOCOCCUS. Br. (1849.) 
Cells united in fours on very short branches, dissimilar, the 
two intermediate contiguous oblique, obtuse ovate, the two 
lateral, opposite and separate from each other, lunate; families 
free swimming, in botryoid clusters. 
This genus is allied to Dictyosphariwm, next to which it should have 
been placed. 
Dimorphococcus lunatus. Br. Alg. Uni. p. 44. 
Green, apices of the cells hyaline. 
Sizz. Cells longitudinal diam. -01--02 mm. 
Rabh. Alg. iii. p. 86. Archer, Quart. Journ. Micr. Sci., 
1872, pp. 195, 197. 
Floating in pools. N. Wales. 
We have been unable to make « successful drawing from the 
specimen we possess of this Alga, as we have not seen it living. Mr. 
Archer, on reporting upon its occurrence in Ireland, criticised the only 
figure extant (in Rabenhorst’s Alg. Eur.) in the following terms: ‘The 
upper or outermost cells do not, as they are made to seem, or as the 
original description might lead one to infer, stand above the larger and 
lower (inner) cells as upon a common stipes, but the former grow off 
from the latter, and remain joined thereto by a short pedicle. The inner 
cels are broadly reniform, and two stand opposite to each other at the 
apex of the supporting stipes, so as to present a lunate figure, and from 
the lower part of the sinus made by these it is that the pedicle of each 
of the pair of secondary, more or less reniform, but unequally lobed, 
cells (one from each lower cell) starts, the smaller lobes of these latter 
overlapping each other, and appearing, in a crowded cluster, like one 
cell, only of smaller dimensions, concentrically posed above the lower 
