SYSTEMATIC PART. 



Class RADIOLARIA. 



Radiolaria, Johannes Miiller, 1858.' 

 Ehizopoda radiaria, Johannes Miiller, 1858. 

 Polycystina (pro parte), Ehrenberg, 1838. 

 Echinocystida, Claparfede, 1858. 

 Rhizopoda capsularia, Haeckel, 1861. 

 Cytophora, Haeckel, 1862. 



Definition of the Class : — R li i z o p o d a with unicellular body, divided 

 by a porous membrane into an internal or intracapsular part 

 (with nucleus), and an external or extracapsular part (with 

 c a 1 y m m a) ; propagating by flagellated spores. 



The Eadiolapja or Capsulate Ehizopoda, first constituted by Johannes Miiller in 

 the year 1858 as a separate group of the Ehizopoda, form a peculiar class of the 

 Protista, or iinicellular organisms. This class is exclusively marine, and has in 

 general the characteristic organisation of the Ehizopoda, with the development of 

 numerous j^^^udopodia from the surface of the cell ; but it differs from aU other 

 Ehizopoda in the possession of a j)eculiar membrane, dividing the cell-body into two 

 different parts ; the central capsule or the internal part with the nucleus, and the external 

 part or extracapsidum 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 Centred Capside or the inner part of the Eadiolarian body is constantly composed 

 of three essential parts, viz. : — 



1. The Central Nucleus (a true cell-nucleus). 



2. The Intracapsidar Sarcode (endosarc) or surrounding internal j)rotoplasm. 



3. The Capsxde Membrane or enveloping porous membrane. 



(ZOOL. CHALL. EXP. — PART. XL. 1885.) El 1 



