PLATE I. 



The following abbreviations retain the same significance throughout the present and 

 succeeding Plates : 



n. Nucleus or endoplast. 

 c v. Contractile vesicle. 

 f. Flagellum. 



cl. Collar. 

 o. Oral aperture. 

 an. Anal aperture. 



Where the figures are borrowed from another authority, the name of such authority is 

 bracketed ; where no bracketed name appears the figures are derived from the author's 

 original investigation. 



