+-----+-----+------+-----+------+-----+-----+-----+-------------------+ | | 20. Phæoconchia | +-----+-----+------+-----+------+-----+-----+-----+-------------------+ | 3 | 20 | 73 | 4 | 69 | 0 | D | B | 121-128 | +-----+-----+------+-----+------+-----+-----+-----+-------------------+ | Total, | +-----+-----+------+-----+------+-----+-----+-----+-------------------+ | 85 | 739 | 4318 | 810 | 3508 | 558 | ... | ... | 140 | +-----+-----+------+-----+------+-----+-----+-----+-------------------+ _Note._--In the tenth and eleventh columns the relative abundance of each order at or near the surface and near the bottom is approximately indicated by the letters A-E, which have the following significance:--A, abundant; B, very numerous; C, many (medium quantity); D, few; E, very few. {1}SYSTEMATIC PART. ---- CLASS RADIOLARIA. RADIOLARIA, Johannes Müller, 1858. RHIZOPODA RADIARIA, Johannes Müller, 1858. POLYCYSTINA (_pro parte_), Ehrenberg, 1838. ECHINOCYSTIDA, Claparède, 1858. RHIZOPODA CAPSULARIA, Haeckel, 1861. CYTOPHORA, Haeckel, 1862. _Definition of the Class:_--#Rhizopoda with unicellular body, divided by a porous membrane into an internal or intracapsular part (with nucleus), and an external or extracapsular part (with calymma); propagating by flagellated spores.# The RADIOLARIA or CAPSULATE RHIZOPODA, first constituted by Johannes Müller in the year 1858 as a separate group of the Rhizopoda, form a peculiar class of the PROTISTA, or unicellular organisms. This class is exclusively marine, and has in general the characteristic organisation of the Rhizopoda, with the development of numerous _pseudopodia_ from the surface of the cell; but it differs from all other Rhizopoda in the possession of a peculiar _membrane_, dividing the cell-body into two different parts; the _central capsule_ or the internal part with the _nucleus_, and the external part or _extracapsulum_ with the _calymma_; propagation by flagellated spores produced in the central capsule; the sarcode or the _protoplasm_ of both parts communicates by fine _pores_, piercing the separating membrane, which is called the _capsule-membrane_. The _Central Capsule_ or the inner part of the Radiolarian body is constantly composed of three essential parts, viz.:-- 1. _The Central Nucleus_ (a true cell-nucleus). 2. _The Intracapsular Sarcode_ (endosarc) or surrounding internal protoplasm. 3. _The Capsule Membrane_ or enveloping porous membrane. {2}Besides these constant and essential elements, the central capsule contains very commonly (but not constantly) some other enclosed structures, viz.:-- 4. An internal or intracapsular skeleton. 5. Intracapsular vacuoles or alveoli. 6. Fat-granules or oil-globules. 7. Crystals of different composition. 8. Pigment-granules.