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PACIFIC SCIENCE, Vol. XI, April, 1957 
laying in the population in Algeria. The eggs 
are incubated by the female (Durchon, 1956). 
The larvae of Nereis diversicolor and Neanthes 
lighti resemble those species given above, but 
differ in their site of development. This pro- 
ceeds on the substrate in N. diversicolor (Dales, 
1950) and in the coelom of viviparous N. 
lighti (Smith, 1950), 
Only two of the species studied have eggs 
with a large amount of yolk, giving rise to 
nereidogenic larvae. In both of these species, 
the male incubates the eggs within a mucoid 
tube, a ciliated embryonic stage is lacking, 
there is no larval planktonic stage, and the 
adults do not undergo metamorphosis into 
epitoky prior to sexual maturity. One of these 
two species, Platynereis massiliensis , has been 
studied by Hauenschild (1951) who found it 
to be a protandric hermaphrodite. The other is 
Neanthes caudata , whose life history is dis- 
cussed in this paper. 
It certainly appears from this summary that 
the method of reproduction and development 
of Neanthes caudata is unusual among the 
nereids. But only a few species have been 
studied and there is too little information 
available as yet to make any positive statement 
on this subject. As no correlation is apparent 
between genera and mode of reproduction, 
the life history of each species must be worked 
out before any authoritative conclusions can 
be reached. 
SUMMARY 
1. Reproduction and development in the 
polychaete family Nereidae was reviewed 
and summarized in Table. 1. 
2. Neanthes caudata was reported from the 
Pacific Ocean for the first time. It was 
taken from suspended sediment bottle col- 
lectors and from the bottom of Los An- 
geles-Long Beach Harbors. 
3. Techniques for rearing N. caudata through 
sexual maturity were described. 
4. Males and females are attracted to one 
another, whereas individuals of the same 
sex fight with one another. This behavior 
is altered in the male while he is incubating 
the developing ova; he fights either sex. 
5. A sex ratio of one to one was found in 
laboratory-reared specimens. 
6. Spawning was not seen. The female died 
or was eaten by the male following egg- 
laying. The male incubated the eggs within 
its mucoid tube. The male may reproduce 
more than once. 
7. The ova ranged in size from 420 to 520 \i 
in diameter. Fertilization was not observed. 
Cleavage proceeded very slowly. The four 
macromeres did not undergo further cleav- 
age beyond the eight-cell stage. The micro- 
meres continued to divide and gradually 
surrounded the macromeres by epibolic 
growth. The embryo was not ciliated. The 
three larval segments with setae appeared 
at eight days. The larvae left the parent 
tube at 21 days. Feeding commenced 
shortly thereafter. Sexual maturity was 
reached in both sexes in 65 days. The F 2 
generation reproduced 83 days later and 
the F 3 generation 65 days later still. The 
sequence in the life history was summar- 
ized in Table 2. 
8. Neanthes caudata was characterized by a 
sigmoid growth curve with an interrupted 
plateau, when the number of segments was 
used as a measure of growth. The inter- 
rupted plateau was correlated with the 
onset of feeding. 
REFERENCES 
Aiyar, R. Gopala. 1935. Hermaphroditism 
in Lycastis indica (Southern). Current Sci. 
[India] 3: 367-368. 
Anonymous. 1952. Los Angeles-Long Beach 
Harbor pollution survey. Los Angeles Re- 
gional Water Pollution Control Board No. 4, 
Calif. 43 pp. 
Banse, Karl. 1954. Uber Morphologie und 
Larvalentwicklung von Nereis (Neanthes) 
succinea (Leuckart) 1847. (Polychaeta erran- 
