Marshall and Murdoch. — Tertiary Rocks near Hawera. 91 



It has frequently been remarked before by one of us when speaking 

 of the molluscan fauna of the earlier portion of the Oamaru system — 

 notably that of Target Gully — that it was distinctly richer than that of 

 the present day. It is hardly correct to make this statement in speaking 

 of any comparison between the fauna of the Waipipi series and that of 

 the CastleclifT series. The fauna that has been collected from the former 

 locality up to the present time is not very extensive, and it is notably 

 wanting in the smaller species. These facts effectively prevent a complete 

 comparison being made. It can, however., be safely said that, while the 

 Castlecliff fauna contains a large number of species that are not found 

 at Waipipi. most of these additional species have been found elsewhere in 

 Tertiary rocks of greater age than those of the Waipipi series. 



During the time that elapsed between the Waipipi and the Castlecliff 

 periods of deposition, perhaps Upper Miocene to Upper Pliocene, a period 

 elsewhere estimated as equal to a lapse of 690,000 years, an important 

 change took place in the fauna. This change was not the result of the 

 introduction or addition of new species or of new genera, but was due to 

 the extinction of some genera which had been of importance up to the 

 middle of the period, and of numerous species that had given a definite 

 character to the earlier fauna. 



As has already been remarked, the molluscan fauna of the Castlecliff 

 series differs in few respects from the Recent fauna. It is probable that 

 the difference is even less than a comparison of the lists would suggest, 

 for the Castlecliff beds were deposited at a depth that approached 100 

 fathoms, and we have at present an incomplete knowledge of the fauna of 

 the New Zealand bea-floor at that depth. Dredgings that were made 

 outside the Great Barrier in 1904 brought to light several species that had 

 previously been collected in the Castlecliff series, and had been thought 

 to be extinct. From our work on the mollusca of the beds on the Wanganui 

 coast-line we consider that we have a knowledge of at least the main features 

 of the New Zealand marine mollusca from the Upper Miocene to the present 

 day. Such a knowledge must shed an important light on theories that 

 have been advanced in regard to the relations or land connections between 

 New Zealand and other countries during this lapse of time. A number of 

 eminent authorities have written on this subject, but at the present moment 

 we wish to restrict ourselves to those who have made specific statements 

 in regard to these land connections during the period with which we have 

 dealt — namely, from the Upper Miocene to the j>resent day. Hutton* has 

 definitely stated that during the older Pliocene New Zealand was in direct 

 communication with New Guinea. The statement is based mainly on the 

 occurrence of Diplodnn aucklandicus in lignite-beds at the Dunstan, in Otago, 

 a species which is said by Hutton to have its nearest ally in New Guinea. 

 We consider it to be impossible that a continental extension of such a mag- 

 nitude should have occurred without having the greatest effect on the 

 molluscan fauna of New Zealand at that time, and of this we have not been 

 able to find any trace. Marshallf has stated that the great Pleistocene 

 elevation connected New Zealand with some of the northern tropical 

 islands, and provided also a shallow-water connection with Antarctica.' 

 This statement was based on older opinions of Hutton. It is sufficient 



1912. 



* F. W. Hutton, Index Faunae Novae Zealandiae, p. 18, Dulau and Co., 1904. 

 f P. Marshall, New Zealand and Adjacent Islands, p. 49, Carl Winter, Heidelberg, 



