PROTOZOA. 



3 



Order 3. Sarcosporidia. 



The initial stage of the life-cycle occurs in the 

 muscle-cells of vertebrates. (Sarcocystis.) 

 CLASS 4. Infusoria. 



With motile organs in the form of cilia during 

 all or part of the life-cycle. Nucleus dimorphic 

 (macronucleus and micronucleus). Reproduc- 

 tion is by simple transverse division or by bud- 

 ding. 

 Subclass 1. Ciliata. 



With cilia throughout the life-history. 



Order 1. Holotrichida. 



The cilia are of approximately equal length and 

 thickness and equally distributed over the body. 

 Trichocysts are present. (Prorodon, Paramse- 

 cium.) 



Order 2. Heterotrichida. 



With a uniform covering of cilia, together with 

 an "adoral zone" formed of cilia fused into 

 membranelles. (Spirostomum, Stentor, Halte- 

 ria.) 



Order 3. Hypotrichida. 



The cilia are limited to the ventral surface of a 

 dorso-ventrally flattened body. Cilia often 

 fused into cirri, membranelles, etc. (Oxy- 

 tricha, Pleurotricha, Euplotes, Stylonychia.) 



Order 4. Peritrichida. 



More or less bell-shaped in form. Cilia usually 

 reduced to those constituting the adoral zone. 

 (Vorticella, Zoothamnium, Lichnophora.) 

 Subclass 2. Suctoria. 



Usually possessing cilia only during the embry- 

 onic stages of the life-history. Tentacles 

 adapted for piercing and sucking are present. 

 (Podophrya, Ephelota, Acineta.) 



Blochmann: Die Mikroscopische Tierwelt des Siisswassers. Abt. 1. Pro- 



tozoa, 1895. 



Biitschli: Protozoa. Bronn's Thierreich, 1889. 

 Calkins: Protozoa, 1901. 



- : Protozoology, 1909. 



- : Marine Protozoa of Woods Hole. Bui. U. S. Fish. Com., 1901. 

 -- : The Scope of Protozoology. Science, 1911. 



Conn: Fresh Water Protozoa of Connecticut. Bui. State Nat. Hist. 

 Surv., 1905. 



