IXFUSOIUA. 



1'Jl 



a latticed shell. The extra-capsular cells [yellow bodies] are wanting. Acantlio- 

 tuetra pelliicida Joh. Miill. 



II. Pvlycyttaria. Kadiolaria which form colonies with several central capsules- 

 Amongst the Sphserozoa a skeleton is wanting or consists of single pieces not 

 joined together. Collozoum inermc E. Haeck. Spliesrozoum punctatum Joh. 

 Mlill. In Collosphara the skeleton consists of simple latticed spheres, each of 

 which encloses a central capsule, Collosphcsra Huxleyi Joh. Miill. 



\ 



\ 



FIG. Io2 Eucyrtidium cranoidtm (after E. Haeckel). 



CLASS II. INFUSORIA.* 



Protozoa with a definite form and provided with an external 

 membrane, bearing either flagella or cilia. Mouth and anus usually, 

 contractile vacuole and one or more nuclei always present. 



Infusoria were discovered towards the end of the 17th century 



* Ehrenberg, " Die Infusionsthicrchen als vollkommene Organismen," 1838. 

 Balbiani, "Etudes sur la Reproduction des Protozoaires," Journ. da la Phy*.. 

 Tom. III. Balbiini, "Recherches sur les phenomeiies sexuels des Infusohv-.'' 



