524 
PROFESSOR W. C. WILLIAMSON ON THE ORGANIZATION 
features leading* to the same conclusion. The structure of the latter forms is diffe- 
rent from that of any existing Radiolarians. Instead of possessing the fenestrated 
skeleton which would allow the calcareous ooze, constituting the matrix, to penetrate 
freely into the interior of each sphere-cavity, all such intruded material has been 
absolutely excluded from those cavities. The interior of each is occupied, not by 
amorphous matter like the investing matrix, but by crystalline calcic carbonate, a 
solution of which had obviously filtered through the porous sphere-wall, and crystallized 
within the interior of a closed cavity. In this respect the conditions of the objects 
correspond exactly with those of the carboniferous Foraminifera, which I find associated 
with them ; I am convinced that no known Radiolarian would exhibit similar con¬ 
ditions. Then their form is more like that of the Foraminiferous Orbulina than any 
Radiolarian. Occasionally chance sections like figs. 73 and 76 remind us of a Dictyoca ; 
but other specimens, such as figs. 74 and 77, show that these apparently regular sym¬ 
metrical forms and arrangements of the spines are not characteristic of the organisms. 
Even in fig. 7 6 the second unsymmetrical spine to the right hand of the figure is fatal 
to the idea of the object being a Dictyoca. It is obvious that these organisms were 
closed spheres with a sphere-wall so nearly solid as to exclude all inorganic matter save 
such crystalloids as were in a state of solution, and which, consecpiently, were capable 
of reaching the sphere-cavity by infiltration. 
But a further difficulty stands in the way of our regarding these objects as Radio¬ 
larians. Unable generally to accept Mr. Sollas’s hypothesis of the replacement of 
silica by calcareous matter, I am still less able to do so in the case of the objects under 
consideration. I have already said that such a hypothesis is wholly inapplicable to 
the C. robusta (fig. 81), and it appears to me equally so to the other forms. Mr. H. 
Beady has arrived at the same conclusion. But anxious to obtain the opinion of some 
of our leading chemists on this point, I showed my specimens to Professors Bdscoe and 
Schorlemmer, and they both express their inability to understand how such a sub¬ 
stitution could take place. I presume that on the subject of organic chemistry no higher 
authority than Professor Schorlemmer could be appealed to. After examining my 
specimens, he writes to me as follows : “ I don't know what morphological evidence you 
may possess rendering it probable that the minute calcareous objects in limestone that 
you showed me were originally siliceous animals or organisms; but I should require 
such evidence to be overwhelmingly strong before I should accept such a conclusion. 
I know of no agency by which siliceous structures could be converted into calcareous 
ones, by mineralogical substitution, under the condition in which these organisms 
exist, embedded'in a calcareous matrix. The fact that the silica was of animal origin does 
not appear to me to render the possibility of such a substitution more probable.”* I 
have already shown that such morphological evidence as Professor Schorlemmer 
demands is non-existant—hence I am impelled towards the conclusion that these 
Calcisphcerce were calcareous, and not siliceous organisms, and consequently were not 
* In lit era. Jan. 22, 1879. 
