12 BULLETIN: MUSEUM OF COMPARATIVE 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. 
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 difference, both males and fe- 
males being brick-red, or ochre-red. 
The eggs are greenish-yellow and the 
sperm buff-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 setee appear very early in devel- 
opment. The larva possesses a pair 
of eyes, and remarkably large ecto- 
dermal, cephalic glands. 
Harvarp University, April, 1899. 
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 violent contractions. They pass 
out into the water not only through 
the nephridial openings, but also 
through rents and tears in the body 
wall 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 inales are brown, and the fe- 
males dark green. The eggs are 
green. (See Whitmee, 1875; McIn- 
tosh, 1885.) 
The males and females are about 
equal in number each to each. 
The development is unknown. 
