CH^TOPODA. 
523 
discplouring the sea with their sexual products. They make their ap- 
pearance precisely on the day of the moon’s last quarter, in October and 
November (with intervals of 12, but every 3rd year of 13, lunations ; 
apparently also with a further intercalation about every 30th year), at 
the time of commencement of the rainy season and the change of the 
trade-wind from N.E. to S.E. “ The tenth morning on which the moon is 
seen above the western horizon at dawn is the morning on which the 
Palolo appear.” 
Anatomy, Physiology, &c. 
Some of the species studied by Marion & Bobretzky (6) have also 
been subjected to anatomical investigation, e.g., Saccocirrus [Zool. Rec. 
xi. pp. 493 & 494] ; the segmental organs of the sexual segments are in 
the females transformed into oviducts, in the males into copulatory 
organs ; the females are moreover provided with a pair of copulatory 
pouches and vaginas on the Ventral surface of each sexual segment. 
Mobius (7), p. 161, pi. iii. figs. 21-23 ; Ann. N. H. (4) xiii. p. 260, ob- 
serves that Scolecolepia cirrata carries her eggs in external pouches, com- 
municating -with the body cavity, and placed between the lower feet on 
the posterior portion of the body. 
Panceri (9) has studied the luminous organs in several worms : Chce- 
topterus vario-pedatus^ Polycirrus aurantiacus and medusa, OdontosylUs 
ctenostoma, Polynoe turcica and lunulata, Pholoe hrevicornis, Lumhricus 
terrestris and Balanoglossus minutus. The luminosity is generally due 
to the presence, in the phosphorescent parts, of unicellular glands 
secreting a luminous matter, analogous, through its physical characters 
and its solubility in ether and alcohol, to the fatty substances. In some 
instances, these elements are dispersed over the whole epidermis of 
the animal, which therefore is more or less strongly luminous over 
its whole surface ; in others, they are limited to and concentrated in par- 
ticular places. In Polynoina, the cell-like terminations of the nerves 
of the elytra, in producing the phosphorescence, perform a similar 
function to that performed by the terminal organs of the nerves in 
Phyllirhoe. 
Perrier (10, b) has observed the copulation of Lumhricus fcetidus. 
The copulating worms are kept together by a double membranous ring, 
occupying the length of the 2 “ girdles.” The segments enclosed by 
these rings are precisely those on which the orifices of the copulatory 
pouches and in the interior of which the testes are placed. The sper- 
matozoa, which come from the male orifices (sometimes more than 10 
segments distant), are accumulated under this covering, of which the 
worms get rid, when the copulation is finished, by pushing it towards the 
tail by the means of peristaltic movements. These rings are probably 
formed by a secretion from the “girdles perhaps the egg-capsules are 
formed in a similar way, the “ capsuligenous glands” only secreting 
the albuminous substance in which the eggs are floating. 
Selenka (12) has described and illustrated the (often denied) vascular 
system in Aphrodite. There exists, in fact, a median longitudinal 
