Ferns and Flowering-plants of Mayor Island, N.Z. By H. H. Allan and K. W. Dalrymple. [Read before the Philosophical Institute of Canterbury, 1st October, 1924; received by Editor, 24th October, 1924; issued separately, 6th March, 1926.] Plate 5. Mayor Island (Tahua of the Maori) lies in the Bay of Plenty, north-north-east of Tauranga, about 32 km. (20 miles) from the mainland and beyond the 180 m. (100fath.) depth line. The island, of volcanic origin, is somewhat square, of 1,277 ha. (3,154 ac.) extent, with a high ridge running east and west across the south end, and north and south on the western side, rising to about 396 m. (1,300 ft.) at the north end. The centre of the island is occupied by a great crater, some 8 km. (5 miles) in circumference, in which are two lakes—one of 2.5 ha. (6 ac.), dark blood-red from a distance; the other 8 ha. (20 ac.), of a deep blue-black. The colour is apparently due to the abundance of algal growth. There is a small opening, Opo Bay, on the south-east corner, the usual landing-place. Seaward there are rough water-worn cliffs streaked with veins of obsidian and surmounted by ash-beds sloping into the crater. Dr. L. Cockayne, F.R.S., has kindly forwarded us the notes taken by him on a very brief visit to the island in February, 1905, and the following account of the vegetation is based on these and upon the notes and specimens taken by one of us (K. W. D.) during a fortnight's stay in March, 1924. We have to thank Dr. Cockayne for critically examining certain of the specimens collected. The list of species shows that Mayor Island belongs to the Thames Subdistrict of the South Auckland Botanical District of Cockayne. * See Cockayne, L., 1921. Die Vegetation der Erde, xiv: The Vegetation of New Zealand, p. 300 et seq. Leipzig: Wilhelm Engelmann. The dominant tree is the pohutukawa (Metrosideros tomentosa), many specimens of which are of great size, the largest noted measuring 9 m. in circumference, with a trunk clear of branches for 3 m., and surmounted by a magnificent spreading head. The pohutukawa forms great groves in the lower flats all over the island. The slopes of the main ridges are a continuous succession of small, deep, dry gullies, the spurs of which are clothed in thickets of manuka (both Leptospermum scoparium and L. ericoides), amongst which Knightia excelsa, about 3.5 m. tall, is dotted about. The gully-bottoms have a dense growth of whau (Entelea arborescens), and the side-slopes contain large makomako (Aristoteha serrata) up to c. 0.7 m. in diameter, Litsaea calicaris, Dysoxylum spectabile, Suttonia australis, Brachyglottis repanda, Melicytus ramiflorus, and odd tree-ferns. The liane Rhipogonum scandens is frequent, and the undergrowth is mainly Coriaria sarmentosa, Rhabdothamnus Solandri, and a few ferns. The undergrowth is, however, much altered and depleted owing to the presence of pigs, while the unstable surface militates against regrowth. The high ridges contain a dense scrub in which manuka, Cyathodes acerosa vars., Leucopogon fasciculatus, Coprosma spp., Gaultherio oppositifolia are prominent.