30 (29) Length 8 to 15 mm. Spermatheca single, opening 



midventraliy (Fig. 55). Penis absent 



Monopylephorus parvtis 



Figure 55. — Dorsal view of genitalia, segments X 

 and XI; S, spermatheca; P, prostate. 



30 (29) Length 25 to 46 mm. Spermathecae paired, open- 

 ing medially to line of ventral setae (Fig. 56). 

 Large penis present. . . .Monopylephoms rubronivetis 



Figure 56. — Dorsal view of genitalia, segments X 

 and XI; S, spermathecae; Pe, penis; P, prostate. 



31 (29) Spermatheca single, opening middorsally (Fig. 57). 



Each atrium with two prostate glands 



Phallodriliis monospermathecus 



Figure 57. — Lateral view of genitalia, segments X and 

 XI; S, spermatheca; P, prostate. 



31 {29) Spermathecae paired; open ventrolaterally. Each atrium with no, or one, prostate gland. 32 



32 {31) Length about 10 mm. Setae bifid with subequal teeth (Fig. 58) 

 cylindrical, reflexed distally, each with a com- 

 pact prostate gland (Fig. 59). Male and 

 spermathecal pores in common midventral bur- 

 sae Limnodriloides medioporus 



Figure 58 (top).— Seta. 



Fig^ure 59 (bottom). — Lateral view of male genitalia; 

 A, atrium; P, prostate. 



Atria short, 



32 {31 ) Length 30 to 65 mm. Setae bifid with upper tooth small, rudimentary or 

 absent (Fig. 60). Atria very long, cylindrical, without an external pros- 

 tate gland (Fig. 61). Male and spermathecal pores ventrolateral 



Clitellio arenarius 



Figure 60 (top).— Seta. 



Figure 61 (bottom). — Lateral view of male 

 genitalia; A, atrium; V, vas deferens. 



14 



