450 Transactions.—Dotany. 
up cne side of a ridge to descend on the other. The central cone, which 
forms but a small part of the whole, consists of loose cinders and ashes, into 
which the feet sink at every step of the ascent. The island may therefore 
be regarded as a huge filter, through which the rain percolates, so that a 
perennial stream or even a spring is an impossibility ; in fact, the island is 
entirely destitute of water, except the small quantity that during rainy 
weather accumulates in rock-cavities, and which is speedily evaporated. The 
formation of surface soil is impossible under such conditions, since the 
comminuted particles of rock or ash are washed into the interstices of the 
rocks by every shower, or blown away by every breeze. 
Yet under these antagonistic conditions, less favourable on the whole to 
vegetable life than even the pumice-covered plains of the Taupo district, we 
find a flora comprising fully one-seventh of the entire number of flowering 
plants and ferns indigenous to the colony always exhibiting extreme luxu- 
riance of foliage, although its larger members are greatly dwarfed in stature, 
and at certain periods of the year presenting an amount of floral splendour 
which finds no counterpart in the southern portions of the colony. 
In many places the chasms and depressions are occupied by a most 
luxuriant growth of Mosses, Hepatice, and Lichens, the most frequent of 
which are Hypnum furfurosum, Chandonanthus squarrosus, Dolyotus claviger, 
Trichocolea tomentella, Sendtnera flagellifera, Cladonia rangerifina, C. cornu- 
copoides, ete. On the dry exposed rocks, Racomitrium lanuyinoswn forms 
large patches, which become brittle during intervals of dry weather, but 
revive with the first showers : this is the only locality in which it descends to 
ihe sea-level in New Zealand. Growing amongst the cool mosses are several 
delicate ferns, Hymenophyllum sanguinolentum, H. rarum, H, multifidum, 
and especially Trichomanes reniforme. Other ferns of coarser growth are not 
uncommon, while Cheilanthes sieberi, a characteristic plant of the Auckland 
volcanic district, is plentiful on the driest rocks. One of the most interesting 
plants on the island is the tropical Psilotum triquetrum, which occurs in 
abundance, usually springing from the face of rocks. Dendrobium cunning- 
hamii produces its beautiful flowers in greater profusion and of larger size 
than I have seen them elsewhere, and the fragrant Karina mucronata i8 
abundant. There is a sprinkling of grasses comprising cight or ten species, 
with a few common herbaceous plants, but the most interesting feature of 
the flora is the occurrence of Metrosideros tomentosa, M. robusta, Griselinia 
lucida, Pittosporum crassifolium, Knightia excelsa, and other trees, often in a 
diminutive condition, but laden with glossy foliage of the greatest luxuriance, 
and flowers of deeper and brighter tints than are produced under ordinary 
conditions, 
On the clay cliffs of the adjacent islands, Metrosideros tomentosa attains 8 
