412 



THE INFUSORIA 



Freshwater. GastrostylajlEngelmann. A row of several well-developed ventral 

 cirri. 0'32. Freshwater. Gonostomum, Sterki. Very small peristome. 

 0'20. Marine and freshwater. Urosoma, Kowalewsky. Posterior end drawn 

 out into a long caudal process. Eight abdominal cirri. 0'24. Freshwater. 

 Oxytricha, Ehrb. Five abdominal and five caudal cirri. Caudal spines usually 

 present, but not well developed. - 2. Freshwater and marine. Stylo- 

 nychia, Ehrb. The right margin of the peristorne is bent in an S-shaped 

 curve. Three very long caudal spines (Figs. 72 and 73). 0'4. Fresh 

 water and marine. Histrio, Sterki. Closely related to Stylonychia. Fresh- 

 water. Actinotricha, Cohn. Peristome reduced in size. The left border 



Stylonychia pustulata pre- 

 vious to encystment. The 

 granules of waste matter (Ex) 

 collected in clusters, some 

 of them already, discharged ; 

 M,M, meganuclei ; c.v, con- 

 tractile vacuole. (After Pro- 

 wazek.) 



Fio. 73. 



Cyst of Stylonychia pustu- 

 lata. (After Prowazek.) 



FIG. 74. 



1, Didinium nasvtum, Miiller, one of the 

 GYMSTOSTOMATA, see p. 399. x 200. The pharynx 

 is everted and has seized a Paramoedum as prey. 

 2, Euplotes clMron, Miiller. Side view. A tuft of 

 frontal cirri may be seen in front (right of dia- 

 gram) ; a few abdominal (x) in the middle of the 

 ventral side ; and a group of five (x) forming 

 the transverse row of caudal cirri. 3, Euplotes 

 harpa, Stein, x 150. Ventral view, h, mouth ; 

 x, hypotrichous processes. 



bears a number of large menibranellae arranged in the form of a fan. 

 O'l. Marine. 



Family PSILOTRICHINA, Biitschli. Small forms in which the frontal 

 and abdominal cirri are not clearly differentiated. Balladina, Kow. All 

 the cirri are remarkably elongated. 0'04. Freshwater. Psilotricha, 

 Stein. Anterior end broad, posterior end more constricted. Very broad 

 peristome. O'l. Freshwater. Dipleurostyla, Roux. Freshwater. 



Family EUPLOTINAE, Stein. The principal character is the great 

 reduction in the ciliation of the body. Euplotes, Stein. (Fig. 74, 2.) Peri- 

 etome extensive. Six or seven frontal cirri and a transverse band of five 

 cirri in the caudal region. 0'2. Freshwater and Marine. Diophrys, Duj. 

 The peristome even more extensive than in Euplotes, reaching as far back 

 as the row of caudal cirri. O'l 5. Marine. Uronychia, Stein. The frontal 

 cirri missing. O'l. Marine. 



