36. With three pairs of eyes 37. 

 With only one pair of eyes 38. 



37. Back dark, usually with two dark stripes; with two almost parallel rows 



of eyes 



Glossiphonia complanata (Linn.) 



Body transparent; with two divergent rows of eyes 



Glossiphonia heteroclita (Linn.) 



38. Posterior part of body broadened; with many stripes or spots 



Glossiphonia fusca Castle 

 Body very long and narrow; grayish, brownish or almost colorless 39. 



39. Grayish or brownish, sometimes transparent; with a brown, horny plate 



situated between two rings on the back of segment eight 

 Glossiphonia stagnalis (Linn.) 

 Transparent, almost colorless; no brown, horny plate so situated 

 Glossiphonia nepheloidea (Graf) 



40. With flattened, leaf-like appendages along the sides of the body, or 



with head appendages; mostly marine worms, but with two fresh- 

 water genera near the coast — Class Polychaeta 4L 

 Not so — Class Oligochaeta 42. 



4L With a distinct head and many segments; California 

 l^ereis limnicola Johnston 

 With about thirty-six gill filaments on an indistinct head area; with 

 twelve segments; animal living in a tube; N. J. and Penna. and in the 

 Great Lakes 



Manayun\ia eriensis Krecker 

 (Manayun\ia speciosa Leidy) 



42. Clitellum absent or very narrow, usually beginning on, or anterior to, 



segment eleven; setae or bristles usually distinct, with some of them 

 split or curved or else in groups of more than two; usually, but not 

 always, about one or two inches long; usually, but not always, aquatic 

 — Bristle Worms 43. 



Clitellum usually wide and usually beginning on or posterior to segment 

 twelve; setae usually very minute, simple and usually singly or in 

 pairs; rarely with many setae in a ring-like arrangement around the 

 segments; usually getting to be several inches long; usually, but not 

 always, terrestrial — Earthworms 62. 



43. With one or two setae per bundle 44. 

 With more than two setae in some bundles, either dorsally or ventrally 



(ventral setae may be retractile and difficult to see) 47. 



44. Extremely slender, thread-like; with two, long, separate, ventral setae 



and two, minute, dorsal setae per segment; usually whitish; usually 

 getting to be several inches long; usually terrestrial 



Haplotaxis Hoffmstr. (of Family Haplotaxidae) 



(Phreoryctes Hoffmstr.) 



Moderately stout; setae usually arranged as pairs of curved spines; 



usually with a reddish, dorsal blood vessel giving off side branches 



discernible through the body wall; usually about one or two inches 



long; usually aquatic — Family Lumhriculidae 45. 



90 



