352 



THE CILIATES 



Many species oi Entodinium have been 

 named, but knowledge of the true number 

 and of their correct names awaits some 

 future exhaustive taxonomic study. In the 

 earlier papers, great reliance was placed 

 on caudal spination to differentiate spe- 

 cies, but later it was found that this char- 

 acter varies within a species. Thus, E. 

 caudalum was given its name because it 

 has a long posterior spine on the right 

 side in addition to 2 short, pointed lobes 

 on the left. A second species, E. loboso- 

 spinosum, received its name because it 

 has only a single lobe on the left (the upper 

 one) in addition to the spine on the right. 

 A third species, E. diibardi, has no pos- 

 terior spines or lobes at all. However, it 

 was later found that the caudal spination 

 varies all the way from the caudatiuu type 

 to the dubardi type in several species, and 

 that other characters are more constant 

 and more valuable in differentiating species. 



Six types or classes of caudal spina- 

 tion have been set off along this series 

 for E. caudatmn. Three of them have re- 

 ceived special names, and workers now 

 speak of E. caiidatum forma caudatuni , 

 E. caudatmn forma lobospinosum, and 

 E. caudatum forma dubardi, the last being 

 a form without a tail at all! These same 

 forma names are also used for E. si7?m- 

 lans, and some of them for E. rectangu- 

 latum and E. lobospinosum (cf. Poljansky 

 and Strelkow, 1938; Lubinsky, 1957). 



Entodinium bursa Stein, 1858 has a 

 flattened body which measures about 80 by 

 &Q\x. (Because of the variation in caudal 

 spination, measurements of Entodinium 

 are made nowadays from the anterior end 

 to the cytopyge, but early workers usually 

 gave measurements to the end of the caudal 

 spine. ) The sausage-shaped macronucleus 

 is 4/5 of the body length, and the micro- 

 nucleus is pressed closely to it. The body 

 surface has conspicuous longitudinal stri- 

 ations. The contractile vacuole is an- 

 terior. 



E. minimum Schuberg, 1888 has a 

 flattened body which measures about 40 

 by 22 fi. The right margin of the body is 

 strongly convex and the left margin almost 



straight. The body surface has faint 

 longitudinal striations. The macronucleus 

 is about 1/3 of the body length. The con- 

 tractile vacuole is anterior. 



E. caudatum Stein, 1858 has a flat- 

 tened body about 30 to over 80 p. long. The 

 macronucleus is about half of the body 

 length; it is broader anteriorly than pos- 

 teriorly. The contractile vacuole is near 

 the anterior end of the macronucleus. 

 The upper side of the body is hollowed out 

 to form a groove which broadens poster- 

 iorly. As mentioned above, there is great 

 variation in the caudal spination. 



E. bicarinatum Cunha, 1914 may be 

 a synonym of E. caudatum. It measures 

 about 61 by 35^, and the upper groove is 

 not as deep as in E. caudatum. 



E. furca Cunha, 1914, too, may be a 

 synonym oiE. caudatum. It has 2 unequal 

 caudal projections, 1 on the left and the 

 other on the right, and measures about 52 

 by 27,1. 



E. dentatum Stein, 1859 measures 60 

 to 90 by 30 to 50 p, and has 6 incurved, 

 tooth-like posterior projections. 



E. rectangulatum Kofoid and Mac- 

 Lennan, 1930 measures 23 to 47 by 23 to 

 39 /i. Its body is nearly rectangular as 

 seen from above, except for the caudal 

 spines. The macronucleus is about half 

 the body length and is broader anteriorly 

 than posteriorly. The contractile vacuole 

 is about the middle of the body at the level 

 of the esophagus, i. e. , more to the left 

 than that of E. caudatum. The upper 

 groove is more marked than that of E. 

 caudatum , and its anterior end separates 

 the contractile vacuole from the macro- 

 nucleus. 



E. lobosospinosum Dogiel, 1927 meas- 

 ures 18 to 33 by 13 to 25^ . Its body is 

 rectangular as seen from above. The 

 macronucleus is about half the body length. 

 The contractile vacuole is on the mid-line 

 of the upper side of the body on the level 

 of the micronucleus and to the left of the 

 broad upper groove. 



