358 



THE CILIATES 



surface, a small plate beneath the right 

 surface and a long plate below the lower 

 surface. The pellicle and ectoplasm are 

 thick. There are conspicuous fibrils be- 

 neath the left and upper surfaces. 



Elytroplastron bubali (Dogiel, 1928) 

 measures 110 to 160 by 67 to 97 ^i and 

 has an ellipsoidal body with a smoothly 

 rounded posterior end. There are 4 con- 

 tractile vacuoles along the left midline. 

 This species occurs in the rumen of the 

 water buffalo and zebu. 



Genus OSIRACODINIOM Dogiel, 1927 



The metoral and adoral zones of mem- 

 branelles are at the anterior end. There 

 is a broad skeletal plate beneath the upper 

 side of the body, and a row of 2 to 6 con- 

 tractile vacuoles beneath the left surface. 

 Heavy pharyngeal fibrils are present 

 which extend to the posterior end. 



Ostracodinium mammosuni (Railliet, 

 1890) measures 41 to 110 by 25 to 68 fi 

 and has a left caudal lobe and a right lobe 

 which is hollow on the left side. The pos- 

 terior part of the skeleton extends only 

 2 3 of the way across the upper side. 

 The macronucleus has a large, shallow 

 depression in the middle of its lower side. 

 There are 3 contractile vacuoles. This 

 species occurs in the rumen of the ox and 

 zebu. 



0. gracile (Dogiel, 1925) measures 

 90 to 133 by 42 to 60 |i and has a roughly 

 triangular body with flat right and lower 

 surfaces and convex left and upper sur- 

 faces, and with a smoothly rounded pos- 

 terior end. The skeletal plate extends 

 across the upper surface. The macro- 

 nucleus has 2 lobes. There are 2 con- 

 tractile vacuoles. This species occurs 

 in the rumen of the ox, zebu, sheep and 

 African antelopes. 



O. temie (Dogiel, 1925) measures 59 

 to 76 by 28 to 38 |i and has a slender body 

 with a smoothly rounded posterior end. 

 The skeletal plate extends across the 

 upper surface. The macronucleus has an 

 anterior and a median left lobe. There 



are 2 contractile vacuoles. This species 

 occurs in the rumen of cattle and an 

 African antelope. 



O. Irivesiciilatum Kofoid and Mac- 

 Lennan, 1932 measures 78 to 100 by 42 

 to QO\i and has a triangular body with a 

 smoothly rounded posterior end. The 

 skeletal plate extends across the upper 

 side. The macronucleus has a small, 

 shallow depression in the middle of the 

 lower side. There are 3 contractile vac- 

 uoles. This species occurs in the rumen 

 of the zebu. 



O. quadrivesiculatum Kofoid and Mac- 

 Lennan, 1932 measures 92 to 112 by 43 

 to 56 (i and has a triangular body with a 

 bluntly rounded posterior end. The skel- 

 etal plate extends across the upper side. 

 The macronucleus is elongate and rod- 

 like. There are 4 contractile vacuoles. 

 This species occurs in the rumen of the 

 zebu. 



O. tianum (Dogiel, 1925) measures 

 47 to 70 by 30 to 41 jix and has an ellip- 

 soidal body with a slender, right caudal 

 spine. The skeletal plate extends between 

 the macronucleus and the ventral surface. 

 The macronucleus is short and stout. 

 There are 2 small contractile vacuoles. 

 This species occurs in the rumen of cattle 

 and African antelopes. 



O. gladiator (Dogiel, 1925) measures 

 78 to 112 by 40 to 55 /i and has a slender 

 body with a long, very narrow, right 

 caudal spine. The skeletal plate extends 

 between the macronucleus and the right 

 side. The macronucleus has a lobe on the 

 left anterior end. There are 2 contractile 

 vacuoles. This species occurs in the 

 rumen of cattle and African antelopes. 



O. crassum (Dogiel, 1925) measures 

 120 to 142 by 80 to 100 ^ and has a heavy 

 body with a smoothly rounded posterior 

 end. The skeletal plate extends under 

 only 1/2 of the upper side. The macro- 

 nucleus is short and stout, with a wide, 

 shallow depression in the anterior half of 

 its left side. There are 2 contractile vac- 

 uoles. This species occurs in the rumen 

 of cattle and the steenbock. 



