654 ORDER PERITRICHA. 



an attached endoplastule ; contractile vesicles usually two in number, the 

 one anteriorly and the other posteriorly located. 



Hab. — Endoparasitic within the first and second stomachs of various 

 ruminant Mammalia. 



This genus differs from Ophiyoscolex in the absence of the central girdle of 

 uncinate or setose cilia. Three species are very briefly distinguished by Stein, and in 

 no case has a representation of any one of these been published. 



Eiitodinium bursaria. Stein. — Body long, rounded posteriorly, having a depression 

 in this region, in which the anal aperture is situated ; no caudal spines. 



Enfodinnim dentatum, Stein. — Posterior border armed with six inwardly curved 

 claw-like spines. 



Etitodinium caudatum. Stein. — Inflated dorsally, excavate or emarginate poste- 

 riorly ; the one side bearing a long tail-like spine, and the opposite one two tooth- 

 like points. 



Genus III. ASTYLOZOON, Engelmann. 



Animalcules free-swimming, soft and contractile, more or less campanu- 

 late or pyriform, attenuate posteriorly, and terminating at that region in one 

 or two tail-like, setose appendages ; peristome, ciliary disc, and vestibular 

 cleft as in Vorticella ; anal aperture opening into the vestibulum ; cuticular 

 surface naked, smooth or delicately striate. 



Astylozoon fallax, Eng. Pl. XXXIII. Fig. 29. 



Body irregularly pyriform, tapering posteriorly, and there terminating 

 in two caudal setae equal in length to about one-quarter of that of the entire 

 body ; the dorsal border evenly convex, the ventral one gibbous ; peristome 

 slightly dilated, sloping obliquely towards the dorsal aspect ; ciliary disc 

 not elevated much above the margin of the peristome ; vestibular cleft 

 produced obliquely backwards towards the ventral border ; cuticular surface 

 finely striate transversely ; contractile vesicle situated close beneath the 

 peristome ; endoplast kidney-shaped, subcentral. Length 1-250". 



Hab. — Fresh water. 



This interesting species was described by T. W. Engelmann in the year 1861,* 

 being obtained by him from river water that had been kept isolated for three 

 months, and which yielded under e.xamination no other species of animalcule. 

 Deprived of the characteristic caudal spines, its likeness to a detached zooid of 

 Vorticella or Epistylis was very manifest. Spheroidal encystments were observed on 

 several occasions. 



Fam. VIII. VORTICELLID^, Ehr. 



Animalcules mostly highly contractile, ovate, subcylindrical or campanu- 

 late ; sedentary or temporarily free-swimming, stalked or sessile ; solitary or 

 united in social, dendriform, or mucus-immersed colonies ; naked, or secret- 

 ing indurated sheaths or loricse ; oral aperture terminal, eccentric, associated 

 with an adoral ciliary spire of one or more convolutions, the right limb of 

 which usually descends into the oral entrance or vestibulum, the left one 



* ' Zeitschrift fur Wissenschaftliche Zoologie,' Bd. 4. 



