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University of California Publications in Zoology [VOL. 13 



along the base of the inner adoral lip, the adoral lip strand (ador. lip 

 str.), and that many well-defined fibers passed from it, following the 

 contour of the opereulum towards the right to become lost in the im- 

 mediate vicinity of the base of the right skeletal structure. These are 

 the opercular fibers (op. /.). Most interesting of all, however, was 

 the apparently perfectly definite connection with a ring of substance 

 surrounding the oesophagus at just about the level of the outer adoral 

 furrow. This ring, which is designated as the circumoesophageal ring 

 (circ. oes. ring, figs. B. C; pi. 4, fig. 3; pi. 6, figs. 14-16; pi. 7, fig. 



ador. m. - r 



i. ador. fur. 

 ~ '. ador. lip 

 } r o. ador. fur. 



! o. ador. lip 



tn. m. 



Fig. B. Diplodinium ecaudatum. Semi-diagrammatic representation of an- 

 terior half to show arrangement and relations of neuromotor apparatus. X 1150. 

 ador. lip str., adoral lip strand; ador. m., adoral membranelles ; ant. c. v., anterior 

 contractile vacuole; dr. oes. r., circumoesophageal ring; D., dorsal surface; 

 d. dislc, dorsal disk; d. m., dorsal membranelles; d. m. str., dorsal motor strand; 

 i. ador. Up, inner adoral lip; i. d. fur., inner dorsal furrow; i. d. lip, inner dorsal 

 lip; 1. sk. a., left skeletal area; mac., macronucleus; mic., micronucleus; m. -m., 

 motor mass or motorium; o. ador. -fur., outer adoral furrow; o. ador. lip, outer 

 adoral lip; o. d. fur., outer dorsal furrow; o. d. Up, outer dorsal lip; oes., 

 oesophagus; oes. f., oesophageal fibers (neural fibers) ; oes. retr. str., oesophasreal 

 retractor strands (contractile strands); op., opereulum; op. f., opercular fibers; 

 or., oral opening (cytostome; or. cil., oral cilia; or. disk, oral disk; sk. lam., 

 skeletal laminae; V., ventral surface; v. m. str., ventral motor strand; v. sk. a., 

 ventral skeletal area. 



