5(30 Transactions. 



Pinnoctopus kermadecensis Berry. 



Polypus (Pinnoctopus?) kermadecensis Berry, Trans. N.Z. Inst., 46. 



138, 1914. 

 Eecorded, Berry, I.e. 

 Habitat. — One specimen found on beach, Sunday Island. 



Polypus oliveri Berry. 



Polypus oliveri Berry, Trans. N.Z. Inst., 46, 136, 1914. 

 Eecorded, Berry, I.e. 

 Habitat. — Living among rocks between tide-marks, Sunday Island. 



Argonauta argo Linne. 



Argonauta argo Linne, Syst. Nat., ed. x, 708, 1758. 



Recorded, Iredale, Pro. Mai. Soc, ix, 72, 1910. 

 Habitat. — A few shells washed up on the beaches, Sunday Island. 

 Distribution. — New Zealand, Atlantic, Indian, and Pacific Oceans. 



Argonauta nodosa Solander. 



Argonauta nodosa Sol., Portl. Cat., 96, 1786. 

 Recorded, Iredale, Pro. Mai. Soc, ix, 72, 1910. 

 Habitat. — Both animals and shells occasionally washed up on the beaches, 

 Sunday Island. The description by Berry of a female (Trans. N.Z. Inst., 

 46, 135) probably refers to this species. The largest shell collected at Sunday 

 Island measured 17 cm. in length, and when cast ashore contained the 

 animal. 



Distribution. — New Zealand, Atlantic, Indian, and Pacific Oceans. 



Geographical Relationships. 



Continuous with the orographical axis of New Zealand a submarine 

 ridge with a steep eastern slope falling to one of the profoundest troughs 

 of the ocean extends in a direction about N. 22° E. as far as the Samoan 

 Islands, though actually separated from the elevated area on which that 

 group stands by a channel over 4,000 m. in depth. This ridge over the 

 greater part of its length is less than 2,000 m., and is nowhere over 4,000 m., 

 beneath the surface of the ocean. It is on this ridge, about midway between 

 New Zealand and the Tongan Islands, that the Kermadec Group is situ- 

 ated. To the eastward is an unbroken expanse of ocean over 4,000 m. in 

 depth ; to the westward an area of ocean stretching to the Australian 

 Continent, and whose bed is most irregular, the main features being two 

 basins separated by a submarine ridge trending in a direction north-west 

 from New Zealand towards New Caledonia. The Kermadec Group, there- 

 fore, appears to be situated on the eastern edge of a bygone complex con- 

 tinental area now for the most part submerged. 



In order correctly to understand the geographical relationships and origin 

 of a fauna it is necessary first to investigate the history of the region from 

 a dynamical standpoint, for conclusions as to past changes in land surfaces 

 based on considerations of faunal relationships must be revised if they con- 

 flict with results derived from geological evidence. In the case of the 

 Kermadec Group I have elsewhere* described the structure of the various 



* Trans. N.Z. Inst., vol. 4.°, p. 525, 1911. 



