Marshall and Murdoch. — Tertiary Rocks near Hawera. 95 



perhaps a slightly higher percentage of extinct forms. Nukumaru beach, 

 from the boat-landing to a point one mile to the south of it, has a fauna 

 that shows a somewhat marked difference, not only in the greater percentage 

 of extinct forms and in the occurrence of the genera Melina and Lutraria, 

 but the assembly of species has changed notably. Some of the Recent 

 species are in great abundance, others have distinctly decreased, and others 

 are uniformly distributed ; and in addition to this several are characterized 

 by their unusually large size. 



The Waipipi beds, from a quarter of a mile south of the stream to three 

 miles to the north of it, show a still more marked change of fauna. In 

 addition to the genera Melina and Lutraria, there are Crassatellites, Miltha, 

 Cardium and Olioella, a difference in the assembly of Volutes, Dentalium. 

 Pecten, and Stnithiolaria. The abundance of the individuals of extinct 

 species is somewhat pronounced as compared with the Recent, and the 

 large species are in particular abundance. 



The Whakino-Waihi beds, on the coast near Hawera, have a fauna 

 closely similar to that of the Waipipi beds. The percentage of extinct 

 species is only slightly greater, but there is a difference in the prominent 

 species. Lutraria has not been found ; Melina, Cardium, and Crassatellites 

 are scarce, while Pecten, Natica and Dentalium are in great abundance ; 

 Chione chiloensis is not uncommon. Of the Recent species, Atrina zdandica 

 and Ostrea angasi are in great abundance. 



It has already been pointed out that from Castlecliff to Waipipi there 

 is an unbroken stratified series. We now extend that series to Waihi, and 

 note that within its limits we see a most marked faunal change within a 

 continuous series of deposits. Had it so happened that the beds that lie 

 between the different horizons that are mentioned above had not been 

 preserved, and that the several fragments had been so disturbed that 

 stratigraphical evidence was practically valueless, palaeontology would then 

 have been the only guide to their respective ages. It would have been 

 evident that Castlecliff and Kai Iwi were essentially of the same age. The 

 Nukumaru beds, on the other hand, might well have been regarded as a 

 formation of a different period, and in the Waipipi strata the faunal change 

 is so great that they would probably have been assigned a greater antiquity 

 than they actually possess. On the other hand, the Whakino-Waihi beds 

 are so similar in fauna to those at Waipipi that they would probably have 

 been placed in the same horizon, whereas they are actually separated by 

 several hundred feet of strata. The change in the fauna was slow between 

 the Waihi- Whakino and Waipipi stages, and between the Kai Iwi and 

 Castlecliff stages, but it was relatively rapid between the Waipipi and 

 Nukumaru stages. This rapidity, we think, marks a great change in the 

 physical or climatic conditions of the time. 



It may fairly be claimed that there were no important accessions to the 

 fauna during the Castlecliff to Whakino-Waihi period of deposition, for. 

 as stated previously, the majority of the Recent genera are represented, 

 and usually by Recent species, and the extinct species that occur in any 

 abundance have already been recognized in earlier formations in New 

 Zealand. Even genera such as Couthouyia, Ataxocerithium, and Melina 

 occur at Target Gully, and a fragment of Miltha, perhaps similar to the 

 Waipipi species, lias been collected at Mount Donald. 



While. the Waihi beds are the lowest of the unbroken series of deposits 

 on this coast, and while the palaeontology of the Tawhiti beds as recorded 

 by Marshall, and the Ormond beds as recorded by Henderson and Ongley ; 

 indicate a fairly close relationship, we cannot claim that the one would 



