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Volume 47, 1914
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– 385 –

Waihao Valley.

In this district Mr. Uttley made collections at several different localities, as shown below.

1. Right bank of the Waihao River, three miles below the Waihao Forks, in a bed of greensands which lies conformably below the arenaceous limestone. Ten per cent. of the species are Recent.

  • Turritella concava Hutton.

  • — murrayana Tate.

  • — carlottae Watson.

  • — patagonica Sowerby.

  • Struthiolaria papulosa Martyn.

  • Polinices suturalis Hutton.

  • Galeodea senex Hutton.

  • Alectrion socialis Hutton.

  • Lapparia corrugata Hutton.

  • Ancilla hebera Hutton.

  • Surcula fusiformis Hutton.

  • — n. sp.

  • — n. sp.

  • Bathytoma haasti Hutton.

  • Hemiconus trailli Hutton.

  • Dentalium mantelli Zittel.

  • Limopsis aurita Brocchi.

  • Lima paucisulcata Hutton.

  • Crassatellites obesus A. Adams.

  • Corbula paucisulcata Hutton.

2. Right bank of the Waihao River, at McCulloch's bridge. Here again the fossil-bearing beds consist of greensand which lies conformably beneath the arenaceous limestone. Fifteen per cent. of the species are Recent.

  • Turritella aldingae Tate.

  • — ambulacrum Sowerby.

  • Natica zelandica Q. & G

  • Polinices suturalis Hutton.

  • Mitra inconspicua Hutton.

  • Siphonalia turrita Suter.

  • Ancilla bicolor Gray.

  • Turris n. sp.

  • — n. sp.

  • Surcula pareorensis Suter.

  • Mangilia rudis Hutton.

  • Dentalium solidum Hutton.

  • Corbula canaliculata Hutton.

3. Near Mount Harris, on the slope towards the Waitaki Valley—the first outcrop on the road leading from the Waitaki to the Waihao Valley.

  • Turritella murrayana Tate.

  • — cavershamensis Harris.

  • — concava Hutton.

  • Polinices gibbosus Hutton.

  • Galeodea senex Hutton.

  • Epitonium browni Zittel.

  • Ancilla browni Zittel.

  • — bicolor Gray.

  • Drillia n. sp.

  • Surcula fusiformis Hutton.

  • Dentalium mantelli Zittel.

  • Nucula n. sp.

  • Malletia australis Q. & G.

  • Limopsis aurita Brocchi.

  • Crassatellites obesus A. Adams.

  • Venericardia difficilis Deshayes.

  • Zenatia acinaces Q. & G.

  • Cytherea oblonga Hanley.

  • Psammobia lineolata Gray.

  • Corbula caiparaensis Suter.

  • — canaliculata Hutton.

  • — humerosa Hutton.

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The fossils are contained in a stratum of brown sands, which is the material of which Mount Harris is formed. This material overlies the limestone, and is probably a slightly higher horizon than that of the Target Gully beds. Thirty-three per cent. of the species are Recent.

4. The top of the hill from Waihao Forks to the Elephant Hill. The rocks here again are brown sands similar to those of the last locality.

  • Turritella cavershamensis Harris.

  • — carlottae Watson.

  • Natica zelandica Q. & G.

  • Polinices suturalis Hutton.

  • — huttoni Ihering.

  • Fusinus n. sp.

  • Siphonalia conoidea Zittel.

  • Alectrion socialis Hutton.

  • Fulguraria arabica Martyn.

  • Ancilla bicolor Gray.

  • Marginella pygmaea Sowerby.

  • Surcula fusiformis Hutton.

  • Surcula n. sp.

  • — n. sp.

  • Bathytoma sulcata excavata Suter.

  • Mangilia, n. sp.

  • Terebra costata Hutton.

  • Cylichnella thetidis Hedley.

  • Thalassohelix igniflua Reeve.

  • Dentalium nanum Hutton.

  • — ecostatum T. W. Kirk

  • Crassatellites obesus A. Adams.

  • Venericardia difficilis Deshayes.

  • Corbula canaliculata Hutton.

Of these species, as many as 46 per cent. are Recent.

The general similarity of these lists at once establishes the fact that the rocks in which the fossils occur belong to the same stratigraphical series. This fact is also, in the author's opinion, abundantly proved by the stratigraphical evidence, for no appearance of a stratigraphical break is to be found. Hector and McKay, however, placed these strata in three different formations—Cretaceo-tertiary, Upper Eocene, and Lower Miocene; Hutton placed them partly in the Oligocene and partly in the Miocene; while Park classified them all in the Miocene formation. It is obvious from the foregoing lists that the last opinion is probably correct, though the author differs from Park as to the arrangement of the different beds within this system. The stratigraphical sequence is clearly—

4.

Brown sands.
3.

Grey argillaceous beds (Awamoa).
2.

Limestone.
1.

Greensands.

That this arrangement is supported by the palaeontological evidence is shown by the following considerations: The greensands at Wharekuri contain 23.3 per cent. of Recent species, and those on the Waihao 10 per cent. and 15 per cent. respectively. The lower percentages in the last two cases are based on small and probably quite incomplete collections.

Collections were made from the limestone at Otiake. In this place it has a molluscan fauna which contains 24.2 per cent. of Recent species. Though the limestone has a wide occurrence in the Oamaru district, it seldom contains many molluscan remains, and in most localities the hard and compact nature of the rock makes it almost impossible to extract the shells. In those places only where the limestone is highly arenaceous can the shells be collected with any ease. Park has classified the limestone outcrops at Oamaru in two different series, but we are not able to agree with this from a study of the stratigraphical evidence. The palaeontological evidence as here detailed gives no support to this theory. The fauna of the greensands at Wharekuri and at Waihao appears to be of a distinctly more ancient type than that of the sands which rest on the limestone at Oamaru. Park

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would consider these two strata of the same age. The Oamaru limestone generally consists almost entirely of remains of Echinoderms, Polyzoa, and Foraminifera, though the material is generally somewhat fragmentary.

Near the coast at Awamoa, and actually on the coast at the Rifle Butts and at All Day Bay, the rocks which rest on the limestone are a bluish-grey calcareous mudstone. The percentage of Recent species contained in the Mollusca found in these rocks is 35, 26, and 22 respectively. The divergence between these results is considerable, but the collections are of very different values. It is possible that when the collections are more complete the results will be more in accord.

The Target Gully beds are a slightly higher horizon, and the large collection that has been made there contains 33 per cent. of Recent species. The beds of Mount Harris, in rather similar material, give almost the same result; while those of Elephant Hill, which appear to be a still higher horizon, contain as much as 46 per cent. of Recent species.

Thus the relative number of Recent species gradually becomes greater in the higher beds, as would, indeed, be expected; and it is evident that this result, at the least, strongly supports the conclusion as to the relative position of the strata which was dependent upon purely stratigraphical observations.

As to the actual percentages of Recent species, it is probable that considerable changes will be made in the future as the molluscan fauna of the deeper waters off the New Zealand coasts becomes better known. At the present time relatively little dredging has been done, and it cannot be doubted that several species hitherto believed to be extinct will be yet discovered when further work of that nature has been done. It is, however, evident that none of the strata from which the collections described in this paper have been made is older than the Miocene period. This statement, however, involves the question whether any importance is to be attached to the percentage of Recent species. In a country so geographically isolated as New Zealand it is possible that formal change is very slow and that a relatively high percentage of Recent species may be found in strata of relatively high antiquity.

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