and the other end waving in the water above; several common genera 

 identified mainly by the internal anatomy; two common genera are 

 given here; Family Tuhijicidae 61. 



57. Oesophagus widening suddenly into the intestine 



Henlea Mich. 

 Oesophagus merging gradually into the intestine 58. 



58. Inner setae in setae bundles shorter than the outer setae 



Fridericia Mich. 

 Setae about equal in length 59. 



59. Setae straight 



Enchytraens Henle 

 Setae curved at tips 60. 



60. No sperm sacs; with very few bundles of four setae 



Lumhricillus Orsted 

 With sperm sacs; with several bundles of four setae 

 lAesenchytraeus Eisen 



61. None of the dorsal setae simple-pointed 



Limyiodnlus Claparede 

 Some of the dorsal setae simple-pointed; some usually split into three 

 or more tips 



Tubifex Lamarck 



62. With four single setae per segment; clitellum on segments eleven to 



fourteen; body thread-like; color whitish 



Haplotaxis Hoffmstr. (of Family Haplotaxidae) 

 (Phreoryctes Hoffmstr.) 

 With eight or more setae per segment, usually in pairs, rarely in a ring- 

 like arrangement around the segments; clitellum beginning on or 

 posterior to segment twelve and extending to segment seventeen or 

 beyond 63. 



63. Clitellum beginning after segment eighteen; male pores on a segment 



between twelve and fifteen inclusive; Family Lumhricidae 64. 



Clitellum beginning before segment eighteen; male pores on a segment 



between seventeen and nineteen inclusive 73. 



64. With the prostomium completely dividing the peristomium above; large, 



thick worms 



Lumhricus Linn. em. Eisen Night-crawlers 



(Two common species given here) 65. 



With the prostomium incompletely dividing the peristomium above; 



worms smaller and more slender 66. 



65. Clitellum on segments 3 1 or 32 to 37; color purplish 



Lumbncus terrestris Linn. 

 CHtellum on segments 26 or 27 to 32; color pinkish 

 Lumhricus ruhellus Hoffmeister 



66. Clitellum beginning on segment thirty 



Octolasium Orley em. Rosa 



(Representative species, O. lacteum Orley) 



93 



