EXPLANATION OF PLATE IV. 
Fig. I. — Kawamuria japonica; dorsal and ventral setae, a, dorsal seta; /^^ tip 
of ventral seta. 
2. — The same; diagrammatic representation of penis and coelomic sac, to 
show general relations and to illustrate mode of action of sac. 
3. — The same; male genital organs, diagrammatic, reconstructed from 
sections. 
,, 4. — The same ; section passing obliquely through coelomic sac. x 115. 
,, 5. — The same; section passing somewhat obliquely through lower end of 
coelomic sac and origin of penis; the penis is cut twice, and the sec- 
tion passes through the aperture of the male duct at the distal end of 
the penis, x 115. 
,, 6. — Limnodrilus sociahs ; part of a transverse section through middle of 
body, to show relative positions of dorsal vessel, ventral vessel, and 
ventral nerve cord. x 115. 
,, 7. — The same; chitinous penial tube. x 115. 
,, 8. — Criodrilns bathybaies ; anterior end. 
Figs. 4, 5, 6, and 7 drawn by means of Zeiss's Abbe's drawing apparatus. 
at., athum; a/ v., cavity of coelomic sac; chl., chloragogen cells; cm., circular 
muscular layer; c.s., coelomic sac wall; d.v., dorsal vessel; ej. d., ejaculatory duct; 
^/)., surface epithelium ; /., male funnel; /.w., longitudinal muscular la3^er ; penis; 
par atrium ; per., peritoneum; pr., prostate; s., septum; v. def., vas deferens; 
v.n.c, ventral nerve cord ; v. v., ventral vessel. 
