12 (2) Body wall smooth. Hair setae twisted distally (Fig. 17). Vasa 

 deferentia shorter than atria; prostate gland diffuse (Fig. 18). 

 Coelomocytes large and very numerous. . Monopylephorus irroratus 



Figure 17 (top). — Lateral view of three segments from middle re- 

 gion of body; H, hair seta. 



Figure 18 (bottom). — Diagrammatic lateral view of male genitalia 

 (segment XI) ; P, prostate gland; V, vas deferens. 



V P 



12 (2) Body wall with conspicuous papillae (Fig. 19) or with accu- 

 mulations of foreign particles in ridges of epidermis (Fig. 

 20). Hair setae not twisted distally. Vasa deferentia long- 

 er than atria; prostate gland compact (Fig. 21). Coelo- 

 mocytes absent 13 



Figure 19 (top). — Lateral view of body wall, papillate forms. 

 Figure 20 (middle). — Lateral view of body wall, granulate forms. 

 Figure 21 (bottom). — Diagrammatic lateral view of male geni- 

 talia; P, prostate gland; V, vas deferens. 



13 (12) All or some posterior dorsal setae single-pointed. 

 13 (12) All posterior dorsal setae (crochets) bifid. . . . 



14 

 15 



14 (13) Body wall with large papillae. Dorsal crochets bifid with upper tooth 

 reduced or rudimentary, or single-pointed, or both (Fig. 22). Ven- 

 tral setae with upper tooth shorter than lower (Fig. 23) 



Peloscolex benedeni (in part) 



Figure 22 (left). — Dorsal crochet. 

 Figure 23 (right). — Ventral seta. 



14 (13) Body wall surrounded, at least in part, by accumulated foreign par- 

 ticles; papillae absent. Dorsal crochets bifid with equal teeth up to 

 about segment VI (Fig. 24); dorsal crochets from segment VH 

 long, single-pointed, hairlike. Ventral setae with upper tooth longer 

 than the lower (Fig. 25) Peloscolex intermedius 



Figure 24 (left). — Dorsal crochet, anterior segment. 

 Figure 25 (right). — Ventral seta. 



