The first list of specifically identified fossils from the Chatham Islands was that published by Hutton in his Catalogue of Tertiary Mollusca 1873. Thirteen species were recognised, all except “Gryphaea” tarda represented in New Zealand, and three occurring in the recent fauna. No exact locality had been supplied with the specimens, and as the assemblage did not closely correspond to that of any New Zealand horizon, Hutton thought that more than one formation had been collected from. He says (1873, p. viii.): “The fossils from the Chatham Islands appear to be mixed, as shells characteristic of the Kanieri group, the Ahuriri formation, and the Trelissick group are all in the collection. I think it probable that two formations occur there, one belonging to the Pareora formation, and the other intermediate between the Ahuriri and Oamaru forma-
tions. If, however, there should be only one formation present, I should be inclined to refer it to the Ahuriri period.”
Many of Hutton's specimens have been lost and the exact locality of their origin was never stated, but all except “Gryphaea” tarda probably came from Pitt Island, and formed part of Geological Survey locality collection 792 (H. H. Travers).
A critical examination of the fossils available shows that nearly all of Hutton's records of species common to Chatham Islands and New Zealand are based on wrong identifications.
Many years later, Hutton (1902) described a single fossil, Pecten dendyi, given him by Professor A. Dendy, of Christchurch, and probably collected at Momoe-a-toa where the species is abundant.
During the 1924 expedition, the chief collections of Mollusca were made at four main spots on Chatham Island, and Mr. R. S. Allan was able to make another at Flower-pot Harbour, Pitt Island. In the following year he obtained additional material from these places, and also discovered a new and richly fossiliferous locality on Whenuataru Peninsula, Pitt Island.