10 (7) Rhammites scattered near the entire ventral surface but concentrated around the mouth; seminal vesicle very 

 large so as to almost fill the body in cross section; male antrum with a network of longitudinal muscles 

 running through it (Fig. 17) Genus Fusanlruin. 



Figure 17. — tusantrum rhammiphorum. 



10 (7) Rhammites in rhammite tracts anterior to the mouth; seminal vesicle and male antrum well defined with 

 muscle fibers in the walls (Fig. 18) Genus Endocincta. 



Figure 18. — Endocincta punctata. 



1 1 (6) Male pore in anterior of body close to mouth; tubelike ciliated male antrum (Fig. 19) 



Family ANTIGONARIIDAE (p. 62) 



Figure 19. — Antigonaria arenaria. 



1 1 (6) Male pore not in anterior end; male antrum absent; haptocilia present (Fig. 20) 



Family PARATOMELLIDAE (p. 61). 



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