II 



PHYLUM PROTOZOA 



57 



One genus has a shell formed of agglutinated sand-grains ; in 

 another (Fig. 39, A) the skeleton consists of loosely matted needles 



\1.Raf>hidr'o{jhrys 



c.vcu? 



2. Nude aria 



S.CIaHirulina 



Fia. 39. Various forms of ITeliozoa. 3a, the entire animal; 3b, the flagellula ; c. rac. 

 contractile vacuole ; (7. gelatinous investment; ww. nucleus jisiJ. pseudopods ; sA-. siliceous 

 skeleton ; sp. spicules. (From Butschli's Protozoa, after Schulze and Greeff.) 



of silica. Lastly, in the graceful Clatlirulina (3) the body is 

 enclosed in a perforated sphere of silica, quite like the skeleton of 

 many of the Radiolaria (vide infra}. 



