No. 389.) REVIEWS OF RECENT LITERATURE. 445 
the extreme variability of the Sipunculids in external appearance, and 
the difficulty of specific determination. In Sipunculus australis the 
so-called hooks on the introvert were found to be actually only thick- 
ened cuticular ridges, elevated like rolls above the surface; an 
though characteristic, these structures do not warrant the statement 
of various authors as to the occasional presence of hooks in this 
genus. While the large collections of Sipunculids made by Semper, 
Sluiter, and others, in the Philippine and Malay archipelagoes, have 
yielded a knowledge of the group in these regions superior to that 
from other tropical seas, still Shipley is inclined to look upon the 
Malay archipelago as the center for this group, from which it has 
spread east along southern Asia to the Red Sea, and outward over 
the Pacific and Indian Oceans. The abundance, particularly of cer- 
tain species, in this territory is to be associated with the prevalence ~ 
of coral reefs over the area. nn WwW. 
The Palolo Worm. — The long-existing ignorance concerning this 
interesting annelid that comes to the surface of the ocean during the 
third quarter of the moon in October and November, in the Samoan 
and Fiji islands, has recently been somewhat diminished by the inde- 
pendent researches of Friedlander’ and of Kramer.’ 
We seem now pretty certain that the creature comes from shallow 
water — not from mysterious depths; that it lives in dead coral 
masses; that it casts off the main part of the body to swim free and 
discharge eggs and sperm when ripe, while the head end probably 
remains in the coral to regenerate. The suggestion that it is the 
combined warmth of the sun with least tides that brings on this 
maturity at a particular phase of the moon seems in the right direc- 
tion ; still we remain ignorant of the real cause of this exact periodi- 
city in reproduction. We are not absolutely sure of the genus to 
which the creature belongs — despite the fact that so many Europeans 
have noted its appearance, and that it occurs so abundantly that the 
natives make its capture for food a set feast, and have incorporated 
its habits in their folk-lore. EA A 
Is Fertilization a Process of Feeding ? — N. Iwanzow® describes 
remarkable pseudopodia and tufts of filous threads sent out by minia- 
ture eggs of a helothurian to seize and engulf spermatozoa. In two 
1 Biolog. Centralblatt., vol. xviii, May, 1898. 
2 Ibid., vol. xix, January, 1899. 
8 Bul. ie Imp. Nat. de Moscou, Nr. 3, 1897. 
