THE CILIATES 



351 



FAMILY OPHRYOSCOLECIDAE 



In this spirotrichasin entodiniorid 

 family, there is not more than 1 "dorsal" 

 ("metoral") band of membranelles in addi- 

 tion to the adoral zone. This family con- 

 tains 18 or more genera which occur in 

 the rumen of ruminants; 13 of these occur 

 in cattle and sheep. The most important 

 genera are Eiifodinium , Diplodiniuni, 

 Epidiniiu)! and Ophryoscolex. The taxon- 

 omy of this group is complicated. Varia- 

 tions in structure, even within a clone, 

 are common in EntodiniiiDi and Diplodin- 

 ium. They make species identification 

 difficult and have served to multiply unduly 

 the number of different species which have 

 been named (Polyansky and Strelkov, 1938; 

 Hungate, 1943; Lubinsky, 1957, 1958). 



The body in this family is often flat- 

 tened, and another source of confusion 

 results from the fact that different authors 

 have used the same name for different 

 sides of the body. Depending on whose 

 terminology was used, every one of the 

 four sides has been called the left, right, 

 dorsal or ventral side. Lubinsky (1958) 

 introduced a new system which has the 

 advantages of eliminating the concept of 

 dorsality and ventrality, which actually 

 has no application in this group, and of 

 making it possible to use the same terms 

 both for Entodinium and for the higher 

 genera>in the family. In this system, 

 which is used below, the observer orients 

 the protozoon with its anterior (oral) end 

 pointing away from him (toward 12 o'clock) 

 and with the micronucleus to the left of the 

 macronucleus (toward 9 o'clock). The 

 sides are then designated left (the obser- 

 ver's left, i.e., the micronuclear side), 

 right, upper and lower. 



If this terminology is accepted, then 

 the term, dorsal zone of membranelles 

 (DZM), which is used in describing ophry- 

 oscolecids, is no longer appropriate. 

 Lubinsky used "metoral membranelle 

 zone-' instead. 



Genus OPHRYOSCOLEX Stein, 1858 



The body is ovoid, with adoral and 

 metoral zones of membranelles. The 



metoral zone is some distance from the 

 anterior end and encircles 3/4 of the body 

 circumference at its middle, being broken 

 on the upper right side. There are 3 

 skeletal plates extending the length of the 

 body on the upper right side, and 9 to 15 

 contractile vacuoles arranged in an anter- 

 ior and a posterior circle. The macro- 

 nucleus is simple and elongate. This 

 genus occurs in the rumen and reticulum 

 of cattle, sheep, goats and wild sheep. 

 It is not common, and is seldom present 

 in large numbers when it does occur, but 

 is interesting because of its size and ap- 

 pearance. 



Ophryoscolex inermis Stein, 1858 

 occurs principally in the goat. It meas- 

 ures 170 to 190 by 65 to 100 (i . Becker 

 and Talbott (1927) found it in 1 of 26 cows 

 in Iowa. It differs from the other species 

 of Ophryoscolex in having a rounded pos- 

 terior end, without spines. 



0. purkinjei Stein, 1858 occurs in 

 cattle. It measures 200 by 80 |i and has 

 2 or 3 terraces of thorn-like appendages 

 or spines encircling the posterior end of 

 the body except for a short gap on the 

 right side; in addition, there is a bifid 

 spine at the posterior end. Becker and 

 Talbott (1927) did not find this species in 

 Iowa cattle. 



O. caudatus Eberlein, 1895 occurs in 

 sheep and cattle. It resembles O. purkin- 

 jei but its terminal spine is long and not 

 bifid. Becker and Talbott (1927) found it 

 in 1 of 26 cattle in Iowa. 



Genus ENTODINIUM Stein, 1858 



The body is truncate anteriorly, with 

 the adoral zone of membranelles at that 

 end. There is no metoral zone of mem- 

 branelles, and skeletal plates are likewise 

 absent. The contractile vacuole is anter- 

 ior. The macronucleus is cylindrical or 

 sausage -shaped and dorsal. The micro- 

 nucleus is anterior to the middle on the 

 upper left side of the macronucleus. This 

 is one of the commonest and most impor- 

 tant genera in the rumen and reticulum of 

 cattle, sheep, goats and other ruminants. 



