2 BULLETIN: MUSEUM OF COMPARATIVE ZOOLOGY. 
We will first present an account of the swarming of the Atlantic 
Palolo, and will then give a description of the adult worm, a history of 
the development of its larva, and finally some general conclusions con- 
cerning the breeding habits of Polychete. 
It seems probable that the time of the swarming of the Atlantic 
Palolo is directly related to the date of the last quarter of the moon, 
for in 1898 the swarm occurred on July 9, and the last quarter of the 
moon on July 10; while in 1899 the worm swarmed on July 1, and the 
last quarter of the moon fell on June 29. In 1898 about two hundred 
specimens of the worm were seen to swarm on the morning of July 8, 
but on the following day the animals appeared in vast numbers, while 
on July 10 only about a dozen specimens could be found after a careful 
search. In 1899 a wonderfully dense swarm appeared suddenly on the 
morning of July 1, and only a few worms were to be seen on July 2, 
after which they disappeared. As it was my habit to sail out upon the 
ocean early every morning, I am certain that no other swarms than the 
above-mentioned ones occurred between June 25—August 19, 1898; 
and May 17-July 4, 1899. | 
Description of the Swarming. — The swarming commenced very early 
in the morning before sunrise, and soon vast numbers of the worms 
were to be seen swimming upon the surface of the ocean. Few or none 
of them were to be found in the shallow water near the shore of Log- 
gerhead Key, but at some distance to the westward of the island, where 
the water was between two and five fathoms in depth, they appeared in 
astonishing numbers. The bottom at this place is of coral-sand, and is 
covered with a sparse growth of Gorgonians and Nullipore Algze, while 
nearer the shore the bottom consists of living coral and coral-rock with 
but little sand. When first observed, at four o’clock in the morning of 
the days of the great swarms, the worms presented very much the ap- 
pearance shown in Figure 1, Plate 1. They swam with great activity 
and as near as possible to the surface of the sea. I estimate that there 
may have been about two worms to each square foot of the ocean’s 
surface. The worms were not uniformly distributed, however, but were 
scattered irregularly, sometimes congregating momentarily in wriggling 
masses, such as were likened by Agassiz, in the case of the Fijian 
Palolo, to “thick vermicelli soup.” These congregations are not due to 
any affinity for one another on the part of the worms, but are merely 
the result of accident, for each individual worm swims about quite inde- 
pendently of the others, and shows no tendency to remain in the presence 
of any other which it may chance to meet in its wanderings. The 
