ON THE RADIOL ARIA AS AN ORDER OF THE PROTOZOA. 281 
Thomson’s opinion is not a clerical error, some very interesting 
new forms may be expected to be made known by the publica- 
tion of the “ Challenger ” Zoology ; but whatever novelties may 
be forthcoming, forms without a central capsule should be ex- 
cluded from the Radiolaria .” 
However, with two such admissions before us : — the one that 
the “porous membrane called the capsule,” held by the sup- 
porters of the Eadiolarian classification to form its most important 
characteristic, “ is absent , or exists only in a very modified form 
in the more typical groups ; ” the other, “ that forms without a 
central capsule should be excluded from the Radiolaria ; ” there 
is evidently good ground for hoping that “ this somewhat nega- 
tive class of the Protozoa which,” according to Sir Wyville 
Thomson, 66 has been retained for the reception of animals of 
comparatively simple structure, such as [the Infusoria, whose 
relations we cannot fully make out,” may — to use an expression 
now rendered classical — be abolished “ bag and baggage .” 
It is desirable to mention here that in such Polycystina as 
that figured at page 140 and again at page 150 of Mr. Mivart’s 
memoir, under the name of Eucecryphalus Schultzii , and also 
in the genera Pterocanium , Lithocampe and others, the division 
of the sarcode-body into two or more lobes which are to be seen, 
in the recent condition of these organisms, projecting towards 
the mouth of the shell from its innermost and uppermost portion, 
is not due to the presence of a membranous support, as has often 
been erroneously imagined; but merely to the sarcode being 
prevented from forming itself into a single bulging mass (such 
as we see within the aperture of the tests of Arcella or Difflugia 
when the animal is at rest), by festoon-like processes sent off 
from the interior of the primary chamber ; these processes 
having the effect of constricting the sarcode where it impinges on 
them, without, however, interfering with its free coalescence 
posteriorly. At the same time, if we may judge from what is 
observable in Arcella , it is probable that when the animals of 
the Poly cystine genera above named are in their natural element, 
the lobes may disappear through the flow forwards of the dense 
and sometimes more deeply tinted portion, which, in captured 
specimens, is usually found occupying the innermost part of 
the shell, both in the Polycystina and in some species of Fora - 
minif era. Accordingly, the occurrence of the lobes referred to, 
though furnishing a good distinctive character derived from 
the peculiarity in the configuration of the siliceous framework, 
does not indicate either structural or physiological advance. 
For this reason I have thought it necessary to call attention 
to it. 
[To be continued .] 
