AQUATIC EARTHWORMS 



641 



Sperm-ducts without definite prostate glands and opening into a 

 common median chamber with single ventral median <>|K-n- 

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

 all cleft RJiizodrilus Frank Smith u/x). 



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

 found in roots oi Sagittaria in Illinois. Has two kinds of jjcnital setae 

 on IX and XI; length 75-100 mm.; whitish in ap[)carancc (Smith, lyoo). 

 Michaelsen includes this species in Monopylephorus Levinscn. 



Fig. 989. 



Rhizodrilus lacteus. a, ordinary uncinate seta; b and c, Kcniul N<-ta. 

 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 Tclmalodrilus Eisen iHyg. 



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 Limnodriliis Clapartkie 1S62. 



Several species have been descrif>ed from 

 California (Eisen, 1885). 



L. gracilis Moore has recently been described 

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

 dianiis Ratzel, an abundant si)ecies of wide 

 distribution, the length of the chitinous penis 

 sheath is 8-50 times its diameter. 



Fig. 990. Reproductive organs of Limncdritus 

 gracilis. I, spermary: sp. spermatheca; /. spenni- 

 ducal funnel; r, :, sperm-duct; 6. prostate kIuxI; 

 r, atrium; at, penis and jx-nis sncath; av, ovary. 

 X 20. (.\fter Moore.) 



31 (30) 



Dorsal bundles ordinarily contain capilliform setae and also jx-cti- 

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



Fig 991 a and fi, uncinate setae from 7'M/>f7rx»»ik//i5r/<ir«»J,f and 

 d, palmate setae. T. tnultisrlosus; e and /. jKCtinatc setae. T. 



tubifex. <i, ft, and <, X 150. (DriKinal.) 



?2 (s3) Length of atrium and penis combined, at least two-thirds that of 

 the remainder of the sperm -duct. . Ilyodnlus Eisen iNTQ- 



Three species described from California (Eisen, 1S85). 



