ON THE RADIOLARIA AS AN ORDER OF THE PROTOZOA. 379 
which at once assume the shape of a coronet, inasmuch as they 
present a basal ring, from the upper margin of which, generally 
three principal loops are projected upwards and convergingly in 
a graceful curve, until they meet at a central point where they 
terminate in a single spike, resembling that of a modem helmet. 
From the lateral aspects of the loops, the network forming the first 
or omphalic chamber characteristic of the Monodina , is secreted ; 
all subsequent growth and extension of the siliceous material 
taking place only from the front or opening of the coronet-like 
framework, no matter how many chambers may be produced. 
As already stated both the rudimentary spinelets and the om- 
phalic chambers of the individual, throughout the whole of the 
Polycystina (as formed whilst still within the parent sarcoblast) 
remain constant and determinable to the last, no matter how 
exuberant or even monstrous the growth may, and does very 
often, become. It is this omphalic chamber , and the chamber 
formed subsequently to it, which have very frequently been 
described by writers, who have seen them imbedded in the semi- 
transparent dead sarcode, as the nucleus and nucleolus of the 
sarcode. 
In the concentrically formed division, we find certain plans 
of growth, which might, under a cursory view, be regarded as 
exceptional ; namely, in those examples in which the mature 
framework is not spherical, but compressed so as to assume a 
more or less discoidal, lenticular, or even stelliform shape. But 
even in these forms, and in forms in which we meet with an 
unmistakable admixture of different plans of growth, as if the 
organism had run riot from sheer exuberance of development 
which surrounds the central or normal portion by a network, or 
interrupts one plan of growth and alternates it with another, as 
if doubtful which would suit it best, the omphalostype and 
omphalic chamber remain to the last, and furnish us with 
the most conclusive evidence to be had, that in naming the 
numberless varietal forms which these beautiful structures con- 
stantly assume, any number of cabinet specimens may be iden- 
tified, but not a single step will be gained in our knowledge of 
the causes which produce them. 
EXPLANATION OF PLATE VI. 
N.B. — These figures are all more or less diagrammatic , and meant only for 
the purpose of illustrating the main points in tlie accompanying paper. 
Fig. 1. Lieberhuhnia, (Clap.), showing the central mass of naked sarcode, 
the pseudopodia being omitted for want of room. The object of 
this figure (which is a rough copy of Claparede’s) is to show that 
in the original, sarcdblasts are distinctly visible. As they are 
not yelloio in this genus, Claparede would seem to have failed in 
recognizing them as the representatives of his 11 yellow cells.” 
