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. 



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. 692) 



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. 690) 



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 posterior, connected with vestibule by a long canal; 



reservoir of contractile vacuole distinct; with or without a thin 



stalk Family 2 Ophrydiidae (p. 685) 



Anterior portion not drawn out into a neck 



Without stalk Family 3 Scyphidiidae (p. 685) 



With stalk 



Stalk non-contractile Family 4 Epistylidae (p. 686) 



Stalk contractile Family 5 Yorticellidae (p. 687) 



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; with or without gelatinous 

 envelope; in fresh water. A few species. 



A.fallax E. (Fig. 321, a). 70-100^; fresh water. 



Genus Hastatella Erlanger. Free-swimming; body surface with 

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



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