Chapter 43 

 Order 4 Peritricha Stein 



THE peritrichous ciliates possess a much enlarged disk-like ante- 

 rior region which is conspicuously ciliated. The adoral zone is 

 counter-clockwise to the cytostome viewed from the anterior end. 

 The body ciliation is more or less limited. The stalked forms produce 

 free-swimming individuals, telotrochs. Asexual reproduction is by bi- 

 nary fission; and conjugation occurs commonly. The majority are 

 free-living or attached to various aquatic animals and plants, al- 

 though a few are parasitic. Taxonomy (Kahl, 1935; Stiller, 1939, 

 1940; Nenninger, 1948); structure of stalk (Precht, 1935). 



Attached to submerged objects; usually no body cilia, though telotroch 

 possesses a posterior ring of cilia Suborder 1 Sessilia 



Free-swimming; but with highly developed attaching organellae on 

 aboral end Suborder 2 Mobilia (p. 859) 



Suborder 1 Sessilia Kahl 



Without lorica, although some with a gelatinous or mucilaginous en- 

 velope Tribe 1 Aloricata 



With definite pseudochitinous lorica Tribe 2 Loricata (p. 857) 



Tribe 1 Aloricata Kahl 



Posterior end with 1-2 short spines; swimming with peristome-bearing 



end forward Family 1 Astylozoonidae 



Posterior end, directly or indirectly through stalk, attached to submerged 

 objects 

 Anterior region a long cylindrical, highly contractile neck; contractile 

 vacuole connected with vestibule by a long canal; reservoir of con- 

 tractile vacuole distinct; with or without a thin stalk 



Family 2 Ophrydiidae (p. 852) 



Anterior portion not drawn out into a neck 



Without stalk Family 3 Scyphidiidae (p. 852) 



With stalk 



Stalk non-contractile Family 4 Epistylidae (p. 853) 



Stalk contractile Family 5 Vorticellidae (p. 855) 



Family 1 Astylozoonidae Kahl 



Genus Astylozoon Engelmann (Geleiella Stiller). Free-swimming; 

 pyriform or conical; aboral end attenuated, with 1-2 thigmotactic 

 stiff cilia; pellicle smooth or furrowed; wdth or without gelatinous 

 envelope; in fresh water. A few species. 



A.fallax E. (Fig. 361, a). 70-100m; fresh water. 



Genus Hastatella Erlanger. Free-swimming; body surface with 

 2-4 rings of long conical ectoplasmic processes; fresh water. 



850 



