Marshall. — Fossils and Age of the Hampden Beds. 465 



The following genera have been recorded from the Eocene only in those 

 countries in which they occur : Gilbertia, Belophos. Surcula hamiltoni Suter 

 and Exilia waihaoensis Suter have not been found above the limestone 

 member of the Oamaru system. On the other hand, the genus Tunis 

 (Pleurotoma Lamarck), which is particularly well represented in this col- 

 lection, is a Miocene genus with the single exception of one Australian 

 species of supposed Eocene age ; but there appears to be great doubt 

 as to whether any of the Australian Tertiary formations are really older 

 than the Oligocene, and by far the greater part of them are considered 

 to" be of Miocene age by Chapman. The genus Terebra, again, has no 

 species in strata higher than the Miocene except in the doubtful horizons 

 of Australia. No species of the genus Erato have yet been recorded from 

 any formation below the Oligocene. Struthiolaria has not been found 

 below the Miocene, though Struthiolariopsis has been found by Wilckens 

 in the Cretaceous of South America. The same is true of Malletia. 



Another point of importance is the absence of genera which are usually 

 abundant in the Tertiary formations of New Zealand. Amongst these are 

 Venericardia, Crassatellites, Alectrion, Calyptraea, and Crepidula. With the 

 exception of Venericardia all of these genera are absent also from the beds 

 of Wangaloa. In addition there is the low percentage of Recent species. 

 Too much importance should not be attached to this, for the Onekakara 

 material was deposited in water of considerable depth, and our knowledge 

 of the Recent New Zealand Mollusca from any zone but the littoral is still 

 extremely imperfect. 



So far as New Zealand stratigraphy is concerned, it is probably correct 

 to place the Onekakara beds as slightly higher than the Wangaloa horizon, 

 though they are probably slightly older than the Chatton beds. It is 

 extremely hard to suggest a European equivalent. The palaeontology of 

 the Wangaloa, Onekakara, and Chatton beds strongly support the opinion 

 that there is no geological break in the succession of the lower members 

 of the Younger Rock series of New Zealand, elsewhere called by the author 

 the Oamaru system. Even in these beds at Onekakara, where important 

 Cretaceous and Eocene genera exist, there is still a great number of species 

 that are common in the ordinary Tertiary beds of New Zealand, of which 

 Target Gully can well be taken as a type. They also tend to show that 

 the marginal terrigenous facies shows a variable age when different forma- 

 tions are compared. If the oldest sea-margin. is represented in the beds 

 of the Clarence Valley, as suggested by Thomson,* this margin appears 

 to have extended southwards and westwards gradually. The following 

 seems to be the approximate age of the basement beds in the different 

 localities : Clarence Valley, Cenomanian ; Amuri Bluff, Senonian ; Waipara 

 Gorge, Senonian ; Wangaloa, Maestrichtian ? ;f Chatton, Oligocene ? ; Whare- 

 kuri, Miocene. These Onekakara beds seemed to be more rightly classed 

 with the Eocene than with any other European system. 



The large number of species of common occurrence in the higher Tertiary 

 rocks of New Zealand which occur also in the basement beds of the Otago 

 localities mentioned supports the belief that deposition was continuous in 



* Trans. N.Z. Inst., vol. 48, 1916, p. 57. 



f Mr. C. T. Trechmann, M.Sc, F.G.S., who collected at Wangaloa with me and took 

 a collection away with him, at first regarded the strata as of Maestrichtian age. After- 

 wards he stated that the presence of Pugnellvs appeared to justify a Danian age. 

 (MSS. letter.) 



