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bulletin: museum of compaeative zoology. 



ever, are similar to the sexually 

 developed posterior ones in external 

 appearance. 



The entire worm swims at the sur- 

 face during the breeding period. 



ments are of greater breadth and less 

 length than are the sexually devel- 

 oped posterior segments. (See Fig- 

 ure by Friedlander.) 



The posterior or sexual segments, 

 only, swim at the surface during the 

 breeding period. The anterior por- 

 tion of the worm remains below. 



The eggs or sperm are extruded 

 from the sexual segments by a series 

 of contractions. They pass out into 

 the water not only through the ne- 

 phridial openings, but also through 

 rents and tears in the body wall of 

 the worm, which are often produced 

 by the violence of the contractions. 

 This action usually occurs soon after 

 sunrise. 



There is no well-marked sexual 

 color diflference, both males and fe- 

 males being brick-red, or ochre-red. 

 The eggs are greenish-yellow and the 

 sperm buflf-pink. 



The males and females are about 

 equal in number each to each. 



The segmentation is total and un- 

 equal, and the gastula is formed by 

 epibole. The larva is telotrochal. 

 The setae appear very early in devel- 

 opment. The larva possesses a pair 

 of eyes, and remarkably large ecto- 

 dermal, cephalic glands. 



The eggs or sperm are extruded 

 from the sexual segments by a series 

 of violent contractions. They pass 

 out into the water not only through 

 the nephridial openings, but also 

 through rents and tears in the body 

 w-aU of the worm, produced by the 

 violence of the contractions. This 

 action usually occurs soon after sun- 

 rise. (See Mcintosh, 1885 ; A. Agas- 

 siz, 1898.) 



The males are brown, and the fe- 

 males dark green. The eggs are 

 green. (See Whitmee, 1875 ; Mcin- 

 tosh, 18S5.) 



The males and females are about 

 equal in number each to each. 



The development is ^lnkno^vn. 



IIarvabd UNrvERSiTT, April, 1899. 



