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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 

 s^r.), and that many well-defined fibers passed from it, following the 

 contour of the operculum 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. - 



or. disk 



V. m sir. 



oes. f. - 



sk. lam. ■ 



oes. retr. sir. 



V. sk. a. 



I. sk. a. 



■ i. ador. fur. 

 --- i. ador. lip 

 - o. ador. fur. 



j); o. ador. lip 



m 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; cir. oes. r., circumoesophageal ring; D., dorsal surface; 

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

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

 lip; I. sk. a., left skeletal area; mac, maeronucleus; viic, micronueleus; 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. lip, outer dorsal lip; oes., 

 oesophagus; oes. f., oesophageal fibers (neural fibers) ; oes. retr. str.. oesoi»baueal 

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

 or., oral opening (cytostome; or. oil., 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. 



