Introduction

During earlier work (E. M. Stephenson, 1951, 1952), skeletal material of L. hamiltoni McCulloch was not obtainable, and descriptions were confined to L. hochstetteri Fitzinger and L. archeyi Turbott. Shortly afterwards, a single specimen of L. hamiltoni from Stephens. Is in Cook Strait was made available through the courtesy of the Hon. Minister for Internal Affairs, Wellington, and Mr. W. H. Dawbin, then of the Victoria University of Wellington. The head of this frog was sectioned and a brief comparison was made between it and the heads of the other two species (E. M. Stephenson, 1955).

At the time of publication of the results of recent field studies on L. archeyi and L. hochstetteri (E. M. and N. G. Stephenson, 1957), the distribution of L. hamiltoni was thought to be confined to a small area on Stephens Is. Because of this rarity of occurrence, the gift of a second specimen of L. hamiltoni, a male of apparently advanced age, by Mr. W. H. Dawbin, was of particular value. The specimen in question had been kept in captivity by Mr. Dawbin for some time. After preparation of the frog as an alizarin transparency, a general comparative survey of the skeletons of the three species was begun. Obviously, the material of L. hamiltoni was far too limited to be satisfactory, but it was thought unlikely that more would be available.

In 1957, an unexpected and extremely important discovery occurred Mr. B. Bell, of the Wild Life Branch of the Department of Internal Affairs, reported to the Department that frogs of L. hamiltoni type had been discovered on Maud Is. in Pelorus Sound. One of these specimens was sent to me at the request of the Secretary for Internal Affairs in an endeavour to ascertain whether the Maud Is. frogs should be assigned to a new species. Two more frogs were later supplied at my request. In addition, Mr. Bell carried out an extensive series of measurements of frogs on Maud Is. and these were compared with the measurements of a specimen of L. hamiltoni in the Dominion Museum and one in the Canterbury Museum.

As far as could be judged from all the evidence available, no justification for a change in the specific status of the Maud. Is frogs existed, but the discovery of a new and more favourable locality than Stephens Is for L. hamiltoni was, of course, of very great importance. A key to the species and a discussion of the name for the family are to be found in a recent publication (E. M. Stephenson, 1960)