THE CILIATES 



357 



The pellicle and ectoplasm are thick. 

 There are 2 contractile vacuoles with 

 heavy membranes and prominent pores. 



Eudiplodinium maggii (Fiorentini, 

 1889) measures 104 to 240 by 63 to 77 [i 

 and has a roughly triangular body with a 

 smoothly rounded posterior end. It occurs 

 in the rumen and reticulum of the ox and 

 zebu. 



Genus DIPLOPLASTRON 

 Kofoid and MacLennan,1932 



This species occurs in the rumen of sheep, 

 goats and cattle. 



M. ypsilon (Dogiel, 1925) measures 

 110 to 152 by 60 to 12 ji and has an oval, 

 flattened body with a rounded posterior 

 end. The anterior lobe of the macronu- 

 cleus is small, and there is no posterior 

 lobe. The skeletal plates are fused pos- 

 teriorly. This species occurs in the 

 rumen of cattle. 



Genus POLYPLASTRON Dogiel, 1927 



The metoral and adoral zones of mem- 

 branelles are at the anterior end. There 

 are 2 skeletal plates beneath the upper 

 surface. The macronucleus is narrow and 

 rod-like. There are 2 contractile vac- 

 uoles below the left surface, separated 

 from the macronucleus. 



Diploplastron affine (Dogiel and Fedor- 

 owa, 1925) measures 88 to 120 by 47 to 65jLt 

 and is more or less ellipsoidal. It occurs 

 in the rumen of cattle, sheep and goats. 



Genus MEIADINIUM 

 Awerinzew and Mutafowa, 1914 



The metoral and adoral zones of mem- 

 branelles are at the anterior end. There 

 are 2 skeletal plates beneath the upper sur- 

 face which are sometimes fused poster- 

 iorly. The macronucleus has 2 to 3 left 

 lobes. There are 2 contractile vacuoles. 

 The pellicle and ectoplasm are thick. 

 There are conspicuous esophageal fibrils 

 beneath the left and upper sides. 



Metadiniuni medium Awerinzew and 

 Mutofowa, 1914 measures 180 to 272 by 

 92 to 170 |u and has a heavy body with 

 large membranelle zones. The skeletal 

 plates are narrow. This species occurs 

 in the rumen of the ox and zebu. 



M. tauricum (Dogiel and Fedorowa, 

 1925) measures- 185 to 288 by 70 to 160 ;i 

 and has a heavy body. The skeletal plates 

 are fused posteriorly. The anterior and 

 median lobes of the macronucleus are 

 large, and the posterior lobe is small. 



The metoral and adoral zones of mem- 

 branelles are at the anterior end. There 

 are 2 separate or fused skeletal plates 

 beneath the upper surface, and 3 longi- 

 tudinal plates with anterior ends connected 

 by cross bars beneath the lower surface. 

 There is a longitudinal row of contractile 

 vacuoles beneath the left surface, and 

 others in other locations. 



Polyplastron multivesiculatum (Dogiel 

 and Fedorowa, 1925) measures 120 to 190 

 by 78 to 140jLt and has an oval body with a 

 smoothly rounded posterior end. There is 

 a row of 4 contractile vacuoles near the 

 macronucleus, plus 2 beneath the left sur- 

 face, 1 beneath the right surface and 2 be- 

 neath the upper surface. The 2 upper 

 skeletal plates are separate. This species 

 occurs in the rumen of cattle and sheep. 



P. fenestratum Dogiel, 1927 resem- 

 bles P. multivesiculatum except that the 

 upper skeletal plates are partly fused. 

 This species occurs in the rumen of cattle. 



P. monoscutum Kofoid and MacLen- 

 nan, 1932 resembles P. multivesiculatum 

 except that the upper skeletal plates are 

 completely fused to form a single broad 

 plate. This species occurs in the rumen 

 of cattle. 



Genus ElYTROPLASTRON 

 Kofoid and MacLennan, 1932 



The metoral and adoral zones of mem- 

 branelles are at the anterior end. There 

 are 2 skeletal plates beneath the upper 



