48 PROCKEDINGS OF THE MALACOLOGtCAr. SOCIKTV. 



tlie four recognized, but unnamed, two further additional genera 

 occur. When, however, the species are separately contrasted, the 

 differences become more marked still. I will take thera in the order 

 of the tables above given, and this will conduce to facile reference. 



Parachiton mestayercs, Iredale, cannot be compared, as it is more 

 than probable that this genus extends all over this part of the Pacific 

 Ocean, the only other species of the genus, P. acuminatus, Thiele, 

 having been described from Duke of York Island. There is a small 

 species of Lepidopleurus found on each group, and, though they seem 

 closely allied, verv little stress can be laid upon this, as the small 

 species of Lepidopleurus vary little over large areas. The Kerraadec 

 species is very distinc, as is that from Lord Howe Island. Hedley 

 and Hull compare the Norfolk Island species with the New South 

 Wales form, whilst it clearly recalls to me the Kermadec shell. 



I have differentiated two forms of Eudoxochiton from the Kermadecs, 

 and this genus is otherwise restricted to New Zealand with two species, 

 and nothing nearly related occurs on Norfolk Island, Lord Howe 

 Island, or the Australian continent. In consequence I lay great 

 stress on this occurrence. A species of Plaxipliora was also found at 

 the Kermadecs, whilst no form referable to the family was obtained 

 at Lord Howe Island or Norfolk Island. Tlie Kermadec species was, 

 moreover, referable to the sub-genus Maorichiton, which is common 

 throughout New Zealand, but which does not occur in Australia. 

 This seems of great import to me. 



From Norfolk Island a species of Acanthochites was recorded, which 

 is considered by Hedley & Hull close to the Australian A. grano- 

 striatus, Pilsbry. The species also occurred on Lord Howe Island, 

 where it was accompanied by another species which Hedley & Hull 

 compare with the Australian A. contatus, Adams & Angas. It should 

 be noted that we do not yet know the small species of Acatithochites 

 from New Caledonia and Fiji, and the New Caledonian A. tridacna, 

 Roehebrune, would seem to belong to the A. costatus group, whilst we 

 know species not unlike A. grafiostrtdttis, Pilsbry, from North of 

 Australia. Two small species of Acanthochites were noted as valves 

 in dredgings at the Kermadecs, but no complete specimen was obtained. 

 Of peculiar interest, however, was the collection of a valve which 

 I refer to Cryptoconchus, a genus almost peculiar to New Zealand. 

 Tlie genus hchnochiUm was not represented at Lord Howe Island, 

 though a species was found at Norfolk Island, and I have separated 

 the Kermadec form, which, looks so similar, that Hedley & Hull 

 Considered it identical. The' characters in this group, however, are 

 so slight, that I do not feel justified in advocating tlieir identity. 

 The absence of the genus Ischnochiton from Lord Howe Island cannot 

 be explained at present, but it may be that this genus is also absent 

 or ill-represented in New Caledonia. 



The Neozelanic Sypharochiton is represented at the Kermadecs by 

 the form I have called S. themeropis. A species which recalls this 

 occurs both at Lord Howe Island and Norfolk Island. Hedley and 

 Hull remarked that the Kermadec species might be identical, but the 

 internal features are very different, and I feel very doubtful whether 



