208 THE PROTOZOA 



Order 2. HETEROTRICHIDA. Ciliata characterized by the possession of a uniform 

 covering of cilia and an adoral zone, consisting of short cilia fused together into 

 membranelles. 



Suborder 1. POLYTEICHINA. Heterotrichous ciliates provided with a uniform 

 coating of cilia. 



Family 1. Plagiotomidae. The peristome is a narrow furrow, which begins, as a 

 rule, close to the anterior end, and runs backward along the ventral side to the 

 mouth, which is usually placed between the middle of the body and the posterior 

 end. A well-developed adoral zone stretches along the left side of the peristome, 

 and it is usually straight. Genera: Conchophthirus Stein ('61); Plagiotoma 

 Duj. ('41) ; Nyctotlierus Leidy ('49), a sub-genus; Blepharisma Perty ('49); 

 Metopus Clap. & Lach. ('58) ; Spirostomum Ehr. ('35). 



Family 2. Bursaridae. The body is usually short and pocket-like, but may be 

 elongate. The chief characteristic is the peristome, which is not a furrow, but a 

 broad triangular area, deeply insunk, and ending in a point at the mouth. The 

 adoral zone is usually confined to the left peristome edge, or it may cross over to 

 the right anterior edge. Genera: Balantidmm Stein ('67); Balantidiopsis 

 Butschli ('88); Condylostoma Duj. ('41); Bursaria O. F. Miiller (1773); 

 Thylakidium Schewiakoff ('92). 



Family 3. Stentoridae. The peristome is relatively short and limited to the front 

 end of the animal, so that its plane is nearly at right angles to that of the longi- 

 tudinal axis of the body. The adoral zone of cilia either passes entirely around 

 the peristome edge, or ends at the right-hand edge. The surface of the peri- 

 stome is spirally striated and provided with cilia. Undulating membranes are 

 absent. Genera: Climacostomum Stein ('59) ; Stentor Oken ('15) ; Folliadina 

 Lamarck ('16). Genera incerta sedis: Ccsnomorpha (Gyrocorys Stein) Perty 

 ('52) ; Maryna Gruber ('79). 



Suborder 2. OLIGOTRICHINA. Heterotrichous ciliates characterized by the re- 

 duced cilia, which are limited to certain localized areas. 



Family 1. Lieberkiihnidaa. This name was given by Butschli for certain little-known 

 forms, which were at first considered young Stentors. 



Family 2. Halteriidas. The peristome has no cilia, and only a few scattered 

 ones can be found on the ventral and dorsal surfaces. Genera : Strombidinm 

 Clap. & Lach. ('58) ; Halteria Duj. ('41). 



Family 3. Tintinnidae. The body is attached by a stalk to a theca. Inside of the 

 adoral zone of membranelles is a ring of cilia (par-oral cilia). Genera: Tintin- 

 nus Fol. ('89); Tintinnidium Kent ('81) ; Tintinnopsis Stein ('67) ; Codonella 

 Haeckel ('73) ; Dictyocysta Ehr. ('54). 



Family 4. Ophryoscolecidas. Heterotrichous ciliates characterized by a thick cuticle 

 and deep funnel-like peristome. The posterior end is provided with distinct 

 spine-like processes, while the terminal anus is provided with a well-defined anal 

 tube. Genera: Ophryocolex Stein ('59); Entodinutm Stein ('59) ; Diplodinium 

 Schuberg ('88 ). 



Order 3. HYPOTRICHIDA. Ciliata in which the cilia are limited to the ventral surface 

 of a dorso-ventrally flattened body ; they are frequently fused to form larger 

 appendages, the cirri, and an adoral zone of membranelles. The dorsal surface 

 is frequently provided with bristles. A pharynx may be absent or but slightly 

 developed. 



Family 1. Peritromidas. The peristome is but slightly marked off from the remain- 

 ing frontal area. The cilia on the ventral surface are uniform in size and 

 arrangement, and are not differentiated into cirri. Genera : Peritromus 

 Stein ('62). 



