AQUATIC EARTHWORMS 



641 



26 (27) Sperm-ducts without definite prostate glands and opening into a 

 common median chamber with single ventral median open- 

 ing on XI; spermathecal pores on X; setae of dorsal bundles 

 all cleft Rhizodrilus Frank Smith 1900. 



One species thus far known in North America, R. lacteus Frank Smith, 

 found in roots of Sagittaria in Illinois. Has two kinds of genital setae 

 on IX and XI; length 75-100 mm.; whitish in appearance (Smith, 1900). 

 Michaelsen includes this species in Monopylephorus Levinsen. 



FIG. 989. Rhizodrilus lacteus. a, ordinary uncinate seta; b and c, genital setae 

 from IX and XI. X 150. (After Smith.) 



27 (26) Sperm-ducts with definite prostate glands 28 



28 (29) Ten or more small definite prostates on each sperm-duct; no capil- 



liform setae; setae indistinctly cleft and sometimes simple- 

 pointed Telmatodrilus Eisen 1879. 



Two species, T. vejdovskyi Eisen and T. mcgregori Eisen, are found in California. 



29 (28) Sperm-ducts each with one definite prostate gland (Fig. 990). . 30 



30 (31) Dorsal setae all uncinate and similar to ventral setae; penis with 

 chitinous sheath Limnodrilus Claparede 1862. 



Several species have been described from 

 California (Eisen, 1885). 



L. gracilis Moore has recently been described 

 from Lake Erie (Moore, 1906). In L. clapare- 

 dianus Ratzel, an abundant species of wide 

 distribution, the length of the chitinous penis 

 sheath is 8-30 times its diameter. 



FIG. 990. Reproductive organs of Limnodrilus 

 gracilis. t, spermary; sp, spermatheca; /, spermi- 

 ducal funnel; v,v, sperm-duct; p, prostate gland; 

 r, atrium; at, penis and penis sheath; ov, ovary. 

 X 20. (After Moore.) 



31 (30) Dorsal bundles ordinarily contain capilliform setae and also pecti- 

 nate or palmate setae. (Fig. 991.) 32 



FIG. 991 . a and b, uncinate setae from Tubifex multisetosus; c and 

 d, palmate setae, T. multisetosus; e and /, pectinate setae, T. 

 tubifex. a, b, and c, X 150. (Original.) 



32 (33) Length of atrium and penis combined, at least two- thirds that of 

 the remainder of the sperm-duct. . Ilyodrilus Eisen 1879. 

 Three species described from California (Eisen, 1885). 



