Marshall. — Fauna of the lianipcUii Beds. 241 



the memory of the pioneer in the Tertiary palaeontology of New Zealand ; 



(3) Oamaru is the district where nearly the whole system is developed ; 



(4) the rocks are there* more richly fossiliferous in the various horizons 

 than elsewhere, and fuller collections have been made from them. 



My classification of the divisions of the Oamaru system has also been 

 criticized because it is based on the percentage of Recent sj^ecies contained 

 in the faunas of the different ]:)eds. It appears to me that any classification 

 of the divisions of the strata must be based on at least one of the follow- 

 ing considerations: (J) Tlie occurrence of easily recognizable and widely 

 extended lithological horizons, or on a similar succession of strata in 

 different localities ; (2) the occurrence of genera or species of fossils that 

 have a relatively short range in time and are also widely distributed 

 areally ; (3) the general features and relationship of the faunas in the 

 different strata. 



The first of these considerations appears to me to be incapable of general 

 application to the Oamaru system. The rocks of the system have jjrobably 

 a great overlap, and consequently deposits that are strikingly different 

 from one another lithologically may be strictly contemporaneous. 



In Thomson's opinion the areas of deposition have been affected by 

 local diastrophic movements.* I can reasonably hold that no proof has 

 been given of these supposed local distrophic movements in New Zealand, 

 and I can ([uote the Oamaru district, at least, as one in which the Tertiary 

 strata are continuous over a large district without any indication of being 

 affected by local diastrophic action. 



Thomson's divisions of his Notocene appear to be based entirely on the 

 lithological characters of certain beds near Oamaru itself. The descrip- 

 tions that he gives of them are as follows : — 



Awamoan (uppermost stage) — Blue clay of All Day Bay. 

 Hutchinsonian — Hutchinson Quarry beds and concretionary band. 

 Ototaran — Limestone. 

 Waiarekan — Waiareka tuffs and Enfield-Windsor greensands = Nga- 



2)ara greensands. 

 Ngaparan — Coal-measures, sands, conglomerates, and coal-seams. f 



These purely stratigraphical divisions are poorly enough defined from a 

 lithological standpoint, and no mention whatever is made of any palaeonto- 

 logical characters that they may have. It appears almost impossible to 

 correlate any other beds with them. Endless confusion would be caused, 

 too, by attempts to place the various beds at Oamaru in them. Actually, 

 so far as lithological characters are concerned, this classificatioji is almost 

 the same as that proposed by myself and colleagues in 1911, but this litho- 

 logical classification was then stated to be proposed merely because the 

 palaeontological researches up to that time did not, in our opinion, provide 

 satisfactory material for the classification of the strata, and for that reason 

 we refrained from giving stage names for the strata. Now, however, there 

 is, in my opinion, suflficient material to allow me to frame a classification 

 that is based on palaeontological research. 



In making use of our present knowledge of palaeontology the first point 

 that requires notice is that the fossil Mollusca that have been found in each 

 of these divisions of a lithological nature extend in large numbers — 25 to 



* J. A. Thomson, Trans. N.Z. Inst., vol. 49, pp. 400-1, 1917. 

 t J. A. Thomson, Trans. X.Z. Inst., vol. 48, pp. 34, 35, 1916. 



