4U4 Rhizopoda. RADIATA. Porifbra. 
Uiese various removals leave lliis order of animals now, 
we calculate larger quantities, as for example a 
comparatively speaking, a small one, yet it contains a 
cubic yard, the amount surpasses all human concep- 
great number of genera, and the individuals of most of 
tion, and we have difficulty in expressing the result- 
the species are immensely numerous. 
ing number in figures. When we regard in this point 
We must content ourselves with indicating some of 
of view the whole enormous mass of the sea-coasts 
the leading forms of this interesting order of Protozoa 
of the earth, we must conclude that no other series of 
as represented in Plate 1., figs. 1 to 7, including the 
beings can, in regard to number, be compared with 
genera Koljyoda, Ophryoglena, Oxytricha, Stylonichia, 
them. The part they play in creation at the present 
Discocephalus, Chlamidodon^ and Euplotes. 
day is truly wonderful. Banks of sand which impede 
navigation, obstruct gulfs and straits, and fill up bar- 
Order II.— EHIZOPODA or FORAMINIFERA. 
hours, are their work ; and along with corals they assist 
in forming those islands which are every day making 
The species belonging to this order of Protozoa were 
their appearance in the warm regions of the great ocean. 
formerly known to us only by their external coverings 
In former eras of the earth’s surface, the part they 
or shells, and before the animals were discovered were 
played seems still more striking. In the carboniferous 
always considered to belong to the sub-kingdom 
period enormous masses of limestone in Russia have 
Mollusca. They were indeed, from the structure of 
been found composed almost entirely of a single species 
the shell, generally arranged in the class Cephalopoda, 
of Fusolina; and immense quantities occur in the ere- 
under the name of Polythalamia. Dujardin, however. 
taceous formations in France. They were still more 
has lately shown, from his investigations and discovery 
abundant in the tertiary period. The stones of which 
of the living animal, that they are nearly allied to the 
the largest pyramids of Egypt are built are so full of a 
Infusoria. The animals are of a very simple organiza- 
species of Ntimmulites, that these extraordinary erec- 
tion, appearing to be merely a gelatinous mass, or sar- 
tions appear to be almost entirely composed of them. 
code, with no apparent organs or viscera. They creep 
The stone of which the houses and buildings of Paris 
slowly by means of a series of filaments or filiform 
are constructed is so full of a species of Milioln, that 
processes of considerable length, which they protrude 
Paris and the villages in the neighbourhood may be 
through the small holes observable in the shells (see 
said to be built of them. A cubic inch of the stone 
Plates 1 and 2.), and which, when watched in motion. 
from the quarries of Gentilly contains upwards of fifty- 
appear like a drop of gum flowing along the surface of 
eight thousand of these fossil shells, and the beds of 
the substance they move upon. The coverings of these 
which these quarries are composed are of great thick- 
animals are small shells, and consist chiefly of carbonate 
ness and of vast extent. The actual number of such 
of lime. The texture, however, varies considerably ; 
shells is thus inconceivable. 
in some being opaque, of a close texture like porcelain, 
A great many species of Foraminifera or Rhizopoda, 
and without any external indication of pores ; in others 
both recent and fossil, have been described; but the 
being porous, and perforated, especially in the last seg- 
researches of the latest authors upon this class tend to 
ments, with a great many small apertures ; and in a 
throw great doubts upon tbeir value, and give reason 
third class being transparent as glass. 
to believe that, though individually the Foraminifera 
The recent species occur in various parts of the sur- 
are amazingly numerous and abundant, the number of 
face of the globe in immense numbers. The sand of 
distinct genera and species has been very much exag- 
the sea-shore in many places is so completely filled 
gerated. This order has been divided into several 
with them, that it appears half composed of these elegant 
families, which are characterized by the arrangement 
little shells. In the Adriatic Sea four thousand or six 
of the chambers constituting the shell. For illustra- 
thousand have been found in an ounce of sand, and in 
tions of these curious creatures we must refer to the 
the West Indies three million eight hundred and forty 
magnified figures of the families and genera in Plates 
thousand have been found in the same quantity. If 
{Rhizopoda) 1 and 2. 
Class V. — PORIFERA (The Sponges). 
The class Porifera, the last in the zoological series. 
ments, in the majority of sponges, are a number of very 
and the lowest as regards their organization, is com- 
minute needle-shaped, siliceous, or calcareous sub- 
posed of those substances called Sponges, and to which, 
stances called spicula. These bodies vary much in 
amongst many others, the well-known Sponge of com- 
form. In some sponges they are simply of a needle- 
merce belongs. 
like form, slender and cylindrical, and pointed at both 
For a long time it was a disputed point whether 
ends. In other instances they have a small knob 
sponges belonged to the animal or vegetable kingdom. 
at one end, whilst the opposite extremity is pointed, 
and it is only of late years that the evidence has pre- 
giving them exactly the appearance of small pins. In 
ponderated in favour of their animal nature. 
others, again, we find one end transformed into a fork 
Sponge, in the state in which we usually see it, con- 
with two or even three prongs ; or the whole spiculum 
sists of a congeries of horny filaments, interlaced in 
consists of three or four spines of equal length. These 
every direction so as to form a most intricate net-work 
spicula appear to be hollow tubes, closed at both ends. 
of intercommunicating cells. Imbedded in these fila- 
This framework with its inclosed spicula, is, however. 
