MansnaLL.—Aarly Tertiary Molluscan Faunas of New Zealand. 115 
Авт. 9.—Early Tertiary Molluscan Faunas of New Zealand. 
By P. Marssal, M.A., D.Sc., F.G.S., F.N.Z.Inst., Hector and Hutton 
: Medallist. 
[Read ш, Es Wanganui Philosophical Institute, 27th October, 1921; received by 
3rd December, 1921; issued separately, 8th February, 1923.) 
On savaa occasions I have published articles on the fauna of the Hampden 
beds, as season after season of careful collecting has enabled me to record 
more and more of the species that occur in that singular collecting-ground. 
I have ventured to do this because the Mollusca found there are so 
markedly different from the species that are found in the numerous 
Tertiary collecting localities in New Zealand. 
As mentioned in earlier publications, I have compared the Hampden 
fauna with that found at Wangaloa mainly because of the distinct 
Cretaceous facies of some of the fossils found in these two localities. So 
marked is this Cretaceous facies in the case of the Wangaloa area that 
n f an 
based mainly on the occurrence of Gilbertia, Pugnellus * Perit ge an 
olerma together with species of these genera there are a 
number of hen that occur widely in the various Tertiary fossiliferous 
localities of New Zealand. 
When a comparison of this Wangaloa fauna is made with that of the 
Hampden beds it is сва that there is a greater similarity with this than 
with any other Tertiary fauna that has yet been described in New Zea- 
land. Although, however, the resemblances are considerable, the differences 
remain great, and it is with much hesitation that I have suggested that the 
two formations are contemporaneous. So great, however, are the differ- 
ences between these faunas that I have thought it necessary to offer a 
explanation of them, and to justify the inclusion of the two formations 
in one and the same geological series. The explanation that I have 
suggested is based upon the nature of the lithological differences of the 
materials in which the fossils are embedded in the two localities. АЁ 
Wangaloa the matrix is a fine sandstone which contains a few grains of 
glauconite, while at Hampden the rock is an extremely unctuous mudstone 
which contains abundance of glauconite, and frequent small concretions of 
pyrite. It is therefore obvious that the Wangaloa deposit was formed in 
relatively shallow water, and that of Hampden in water of far greater 
depth. This difference in station necessarily implies also a considerable 
difference in the nature of the fauna in the two localities, though it is 
probable that each of them would contain much the same percentage of 
t species. 
This suggestion, though apparently simple and evident, has been entirely 
misunderstood, for Morgan says that Marshall’s ‘ view still seems to 
that Cretaceous and Tertiary faunas flourished at the same time, the 
former in deep water, the latter in shallow water, close to the early 
ilckens, in two bulletins (1921) on the Cretaceous gasteropods of New Zealand, 
*W: 
states that the Pugnellus from Wangaloa is a young form of Conchothyra parasitica. 
The author does not agree with this. 
