TRANSACTIONS OF SECTION D. 609 
the permanently pelagic types—such as the Pteropods and Sayitta—and the tem- 
porarily pelagic—such as the larval stages of sedentary or reptant forms on the 
bottom of the sea or between tide-marks. Moreover, those larvee which come 
from the bottom in fairly deep water pass, more or less, through the whole depth 
at least twice—viz., when ascending as young larve, and when descending as 
larger forms, each stage being useful, for instance, to fishes of different sizes. 
One of the earliest descriptions of the Pacific ‘ Palolo’ is Dr. Gray’s (1847), 
from examples procured by Mr. Stair, and the specimens consisted only of the 
separated posterior region of the body of an annelid found in immense profusion 
in the surface waters at certain seasons, and which are used as food by the natives. 
Mr. Stair then stated that the worms came from the coral reefs. Subsequent 
observers new that they dwelt in fissures and crevices of these rocks at and near 
low-water, and that the swarming of the headless portions as pelagic forms was 
connected with reproduction. The first head was described and figured by Dr. 
J. Denis Macdonald, and it was clearly that of a Eunicid. Now Eunicids are 
very abundant in cracks and fissures of rocks everywhere, and especially in coral 
reefs, but it has yet to be proved that they bore into the latter. Moreover, 
epitokous annelids have been familiar to zoologists for a long time, so that the 
step by which the ‘ Palolo’ of Samoa was connected therewith was brief, for it 
was evidently the posterior region distended by the reproductive elements. The 
main point in Mr. Woodworth’s observations was the demonstration of the 
atokous and epitokous regions of the body im sétw, and as obtained by splitting the 
edges of the honeycombed coral rocks; though this author attaches much 
importance to what he calls the thermotropic or heliotropic reaction of the pig- 
ment-specks borne on the best-developed central segments of the epitokous region 
—in connection with the swarming, it would seem that further investigation is 
necessary—since similar features are observed in other forms devoid of such 
pigment-specks. 
In the Atlantic ‘Palolo’ (Kunice fucata, Ehlers) from the Dry Tortugas and 
Porto Rico a very similar condition prevails, the posterior epitokous, or sexual 
region, being thrown off by the annelid, which lives in crevices of the dead 
and disintegrating coral rock. This posterior region is broader than in the 
Pacific ‘ Palolo,’ and has no pigment-spots, but it swims freely away in the same 
manner within three days of the moon’s last quarter—June 29-July 28, 
In Britain a condition closely approaching that of the foregoing ‘ Palolos’ 
occurs in various forms; e.g., Nereis Dumerilit (And. and Ed.), swarms of which 
occur in various bays, and in Nerets longissima. An allied condition occurs in 
- Syllideans, the Cirratulids (Dodecaceria), and other annelids. 
One of the most interesting Nereids in this connection is the Japanese 
*Palolo’ (Ceratocephale osawai), as recently described by Akira Izuka. The 
species is much used by the Japanese fishermen as bait, and occurs abundantly in 
the littoral region, as ‘well as extends into estuaries, tributaries, canals, and 
ditches, burrowing in mud. It thus approaches the fresh and brackish water 
Nereids from the Pacific Coast and Hawaii. Warly in September it assumes the 
epitokous condition, the males being brownish, the females bright red. The body 
considerably increases in breadth. Then the posterior region, comprising two- 
thirds of the segments, becomes narrower, the animal still being inthemud, This 
posterior region degenerates and is cast off, even before swarming in October and 
November, though a few are found swimming with the remains attached. 
Shortly after the change just mentioned the annelids leave their burrows and 
become pelagic, and discharge their ova and sperms from the posterior aperture, 
The swarming usually occurs in four different periods, lasting a few days—periods 
falling on nights close to the appearance of the new or full moon and just after 
flood tide. Thus the species quite differs from both the Pacific and the Atlantic 
‘Palolo’ in regard to the process. 
1 Ann, Nat. Hist., xix., p. 409, 
1904. RR 
