G. GENERAL NATURAL HISTORY AND ZOOLOGY. 359 



which he states that among the Hydractinia the eggs are 

 developed exclusively at the expense of the epithelial cells 

 of the endoderm, and remain up to the period of their matu- 

 rity surrounded by the elements of the endoderm. On the 

 other hand, the testicle and the spermatozoa are developed 

 at the expense of the ectoderm, the organ resulting from a 

 progressive transformation of the cellular fold, and originally 

 formed by invagination. 



He finds also that in the female spore-sacs there is the ru- 

 diment of a testicle organ, and in the male sacs a rudiment 

 of the ovary. The spore-sacs, therefore, in his opinion are 

 hermaphrodite. The endoderm and ectoderm have there- 

 fore opposite significations. 14 J5, 1874, 450. 



THE PALOLO WORM. 



Among the most remarkable zoological phenomena of the 

 Pacific Ocean may be mentioned the periodical annual oc- 

 currence at a regular date, in immense numbers, of a marine 

 worm known as the palolo (Palola viridis), which appears 

 in immense numbers in the vicinity of Samoa regularly at 

 the time of the moon's last quarter in October or November. 

 Its occurrence is eagerly looked for by the natives, who col- 

 lect it in enormous amount and devour it greedily, both in 

 a fresh state and also prepared in such a manner as to keep 

 it for some time. From a paper by Mr. Whitmee, in the 

 Proceedings of the Zoological Society of London for 1875, 

 we learn that the two sexes are of different colors, and thus 

 readily distinguishable, and that both males and females break 

 up into a great number of small fragments, from which the 

 eggs and the milt escape, so as to produce the necessary fertil- 

 ization. Some idea of the abundance of this worm at the 

 season in question may be gathered from the fact that the 

 sea becomes quite of a milky appearance during this opera- 

 tion. Proc. Zool. Soc, London, 1874. 



OCCURRENCE OF MOA IN NEW ZEALAND. 



Dr. Hector, at the recent meeting of the British Associa- 

 tion, gave a very interesting account of the occurrence of 

 moa bones in New Zealand, under this name including the 

 various species of fossil giant birds, whether of the dinornis, 

 harpagornis, or others. These remains are sometimes found 



