36 Mr. H. J. Carter on Freshwater Rhizopoda 
many specimens of A. oculata, Stein (mihi), in aggregated 
masses of nine or more individuals held together by their united 
sarcodes, in the midst of which were spaces containing large 
cells of homogeneous, semiopake, colourless matter, like those 
of the marine species figured by Stein: but of this a 
form I hope to write more hereafter. 
Figs. 23 & 24 represent yet two more species (or, perhaps, 
varieties) of A. Kichhornii. In both, the plastic investing mem- 
brane is seen to be carried out in an arachnoid form beyond the 
body ; but in fig. 23 only was the nucleus and a portion of crude 
food observed; while in the two specimens of fig. 24 seen (one 
with and the other without the arachnoid expansion) there was 
nothing, according to my notes, but colourless granules. Hence 
this, with the capitate tentacula, makes it look like Acimeta; but 
its general appearance, and the probability that the hastiform 
extremities of the tentacula are merely accumulations of the 
plastic investing membrane, incline me to the side of Actino- 
phrys. 
ACANTHOCYSTIS, nov. gen. 
Acanthocystis turfacea, n.sp. Pl. II. fig. 25. 
This species is described at p. 263 of the ‘Annals’ (ser. 3. 
vol. xii.) and fully illustrated in Pl. II. fig. 25, &c., while a detailed 
account of the illustrations will be found in the ‘ Explanation’ 
to the plate. I have nothing more to add here to my description, 
except that, if A. viridis, Ehr., be A. brevicirrhis, Perty, coloured 
by chlorophyll, as suspected by Claparéde and Lachmann (p.452), 
then the description of the latter given at p. 450 makes it also 
very like Acanthocystis turfacea; but the two descriptions will 
be found to be by no means identical. 
EXPLANATION OF THE PLATES. 
N.B. The tests in Plate I. figs. 1, 5, 7-11, 129, 13 f, 14 a, g, 2,1, m, 
and 26, and in Pl. II. figs. 15 g, 16, 17, 18d, e, and fig. 21, are all drawn 
upon the scale of {th to ~4,th of an inch, in order that their relative sizes 
may be seen. 
All the figures are, of course, more or less diagrammatic, for the purpose 
of description; but nature has been departed from as little as possible. 
Pratt I. 
Fig. 1. Diffugia pyriformis, Perty (mihi), magnified: a, test; 5, grains of 
hyaline quartz; c, pseudopodia; d, “diaphane ; e, dentiagat at- 
tachments of the same to the test; f, sarcode; g, chlorophyll- 
cells; h, food; 7, nucleus; k, k, peace or contracting vesicles ; 
J, acuminated variety of test; m, pyriform variety. 
Fig. 2. The same, spheruliferous nucleus of: a, nucleolus ; 5, imaginary 
section of the same; ¢, central cavity; d, layer of nuclear proto- 
