298 Transactions. — Botany. 



stature and robustness it would seem the more powerful of 

 the two in " the struggle for existence." Be this as it may, 

 0. chathamica is almost exclusively confined to the drier 

 ground just at the edge of the cliffs, in which places 0. semi- 

 dentata is not abundant. Here 0. chathamica forms dense 

 thickets, unmixed for the most part with any other shrubs; or, 

 if growing more in the open, each plant forms a large rounded 

 bush. The branches radiate upwards and outwards from 

 usually several short thick main stems, and are leafy only at 

 their extremities for a distance of about 18 cm. or so. Their 

 ultimate branches are covered with dense white pubescence. 

 The leaves vary in shape, some being merely lanceolate, but 

 others much broader. On the upper surface they are of a vivid 

 green, and either glabrous or show the remains of a pellicle of 

 tomentum ; on the under-surface they are exceedingly tomen- 

 tose with white tomentum. A transverse section of a leaf 

 shows an extreme xerophytic structure — viz., a thick cuticle 

 on the upper surface, a two-layered epidermis, four rows of 

 very close palisade parenchyma of much greater breadth than 

 the spongy parenchyma, strong stereome round the vascular 

 bundles, and the stomata on the under-surface of the leaf 

 protected by the densely interwoven hairs. The leaves spread 

 out horizontally, but point a little upwards. 



Growing underneath the plants of 0. chathamica is a vari- 

 able amount of vegetation, consisting of Lomaria procera, 

 Hydrocotyle sp., Uncinia sp., Ptens esculenta, and here and 

 there a young tree fern. Mr. W. Jacobs tells me that Phor- 

 rriium tenax used to grow abundantly amongst the Olearia 

 chathamica, and that probably the shrubs which I was examin- 

 ing, now 1 m. to 2 m. in height, are simply a new growth since 

 a first burning, perhaps twenty years ago or more. Whether 

 this is so or not, there is at the present time a distinct zone of 

 0. chathamica extending for a distance of 12 m. or more along 

 the south cliffs of Chatham Island, and following the dry ridges 

 inland, but usually only for a short distance ; and there are 

 no traces of this formation elsewhere in the island, except that 

 an isolated plant or two have been found on his run by Mr. 

 Cox. In the north of the island 0. chathamica is altogether 

 absent. On Pitt Island it is represented by the very closely 

 allied species or variety which I am naming dendyi, and 

 which has purple and not white flow y ers, and a different kind 

 of tomentum on the under-surface of the leaf. 



Tableland Dry Ridges. 



The word " dry " is used merely as a comparative term to 

 distinguish the soil of this formation from that of the wet 

 bogs; but it is only dry insomuch as, although very moist, 

 water cannot be squeezed out of it. The summits of many 



