376 PROCEEDINGS OF THE ACADEMY OF [May, 



EE. — Atrium divided into penis sac and sperm reser- 

 voir, the latter with a special prostate gland ; 

 spermathecse confined to X. 

 r. — Sperm ducts long and slender; prostate 

 glands massive. 

 G. — Cuticle more or less completely cov- 

 ered with flattened papillse; capil- 

 lary setae present or absent; no 

 copulatory setse, Tubifex henedeni. 

 GG. — Cuticle without papillse; capillary 

 setae always(?) absent; posterior 

 dorsal setse enlarged and strongly 

 hooked; copulatory setae present 

 on X, . . . . Tubifex hamatus. 

 GGG. — Neither cuticular papillae, capillary 

 setae, nor copulatory setae present; 

 vas deferens very long and penis 

 sac very complex, with spirally 

 wound muscular coats and a tnun- 

 pet-shaped chitinoid penis sheath, 

 Li m nodril us s ubsalsus . 

 FF. — Sperm ducts short and wide; prostate 

 glands diffuse. 



H. — Penes present; genital pores 

 paired ; capillary setae present, 

 Tubifex irroratus. 

 DD. — No penes nor capillary setae ; spermiductal and 

 spermathecal pores median or nearly so ; sperm 

 ducts short and wide ; prostate glands diffuse. 

 I. — Spermathecae paired; setae 

 all distinctly bifid at tips, 

 Monopylephorus glaber. 

 II. — Spermatheca single; bifur- 

 cation of setae often obso- 

 lete, 

 Monopylephorus parvus. 



Paranais littoralis (Oersted) Czerniavsky. 



Nais littoralis Oersted, 1843. 



Enchytrceus triventralopectinatus Minor, 1863, 



Paranais littoralis Czerniavsky, 1880. 



This species was described under the name of Enchytrceus triventralo- 

 pectinaius as long ago as 1863, from New Haven, Connecticut, by Minor, 

 but appears to have escaped subsequent notice in America. I\Iichaelsen 

 places Minor's species doubtfully among the synonyms of P. littoralis. 

 Hitherto budding individuals only have been found, and until the char- 

 acters of the mature reproductive organs of American examples are 

 known the identity of the latter wdth the European species cannot be 



