45. Some of the setae split at the ends 



Lumbriculus Grube 

 Setae or spines simple-pointed 46. 



46. With a finger-like proboscis from the front of the head 



Sutroa Eiscn 

 No proboscis 



Echpidrilus Eisen 



47. Reproducing by fission, often showing a narrowed, clear section through 



the middle; clitellum, if present, much anterior; usually with bright 

 color spots or else transparent, with the blood showing pale red 48. 



Reproducing sexually; with a clitellum (thicker, dull section) in the 

 region of segments ten to twelve in the reproductive season; body 

 usually white or yellowish or else with pulsating hearts and the blood 

 showing bright red 56. 



48. With straight bristles only, which are simple-pointed; body usually, 



but not always, with bright spots of red, yellow or green 

 Aeolosoma Ehrenberg (of Family Aeolosomatidae) 

 With some of the setae split or curved; body usually transparent, with 

 the blood showing pale red; Family T^laididae 49. 



49. No setae on the dorsal surface 



Chaetogaster Baer 

 With setae on the dorsal surface 50. 



50. Posterior end bearing finger-like gill structures 51. 

 No finger-like gill structures on the posterior end 52. 



51. With the two ventral gill structures on the posterior end much longer 



and slenderer than the others 

 Aulophorus Schmarda 

 Gill structures not greatly differing 

 Dero Oken 



52. With a finger-like proboscis from the anterior end 53. 

 No proboscis 54. 



53. Dorsal setae starting on the second segment 



Pristina Ehrenberg 

 Dorsal setae starting on the fifth or sixth segment 

 Stylaria Lamarck 



54. Dorsal setae starting on the second segment 



Tsjaidium Schmidt 

 Dorsal setae starting on the fifth or sixth segment 55. 



55. With one or more of the setae on the sixth segment much longer than the 



setae on the other segments 

 Slavina Vejdovsky 

 Not so — 



l-^ais Miiller 



56. Setae simple-pointed; usually white or yellowish; aquatic or terrestrial; 



Family £nch>'traeidae 57. 



Some of the setae with more than one tip; usually with bright red blood 



showing; usually living in mud with one end buried in a mud tube 



91 



