200 Transactions. 



(2.) The uniformity of the lavas which form the majority of rocks in 

 the area. No anomalies of distribution can be interpreted in the 

 light of lithological differences in these rocks. 



(3.) As a result of prolonged denudation the crater-ring of the Lyttelton 

 volcano has been broken down at its south-western side and a 

 sector completely removed, so that a stretch of comparatively 

 low country, nowhere over 875 ft. in height, and consisting of 

 exposed rhyolites and sedimentaries, separates the northern part 

 of the crater-ring from the other part of the peninsula. This 

 northern part forms the low range usually called the "' Port 

 Hills," and is referred to throughout this paper, as the habitat 

 of Senecio saxifragoides, by this name. 



For a fuller account of the geological features of this area see J. von 

 Haast, Geology of Canterbury and Westland, 1879, and R. Speight, " The 

 Geology of Banks Peninsula" (Trans. N.Z. Inst., vol. 49, pp. 365-92, 1917). 



(b.) Historical. 



Senecio saxifragoides was first described by Hooker in 1853 (Flora Novae- 

 Zelandiae, vol. 1, p. 144), and in the Handbook its discovery is accredited 

 to Lyall (Handbook, p. 159). 



Hooker, Kirk (Students' Flora, p. 339), and Cheeseman (Manual, p. 372) 

 agree in describing S. saxifragoides as distinguished from S. lagopus only 

 in respect of the leaf, which is described as " clothed with shining silky 

 and woolly hair " (Hooker), " silky or villous " (Kirk), " silky or villous " 

 (Cheeseman), upon the upper surface only, and wanting the stout bristle 

 which characterizes S. lagopus and S. bellidioides. Kirk says, " The leaves 

 are often glabrous or glabrate on the upper surface, but never bristly as 

 in S. lagopus." Cheeseman says, " A handsome species, separated from 

 large states of S. lagopus, some of which approach it very closely, by the 

 much stouter habit, more copious villous hairs, and larger thicker leaves, 

 which are silky above and never show the stout bristly hairs so charac- 

 teristic of S. lagopus and S. bellidioides." 



All agree that these three species, *S. lagopus, S. bellidioides, and S. 

 saxifragoides, are very closely allied. Hooker (Handbook) says, ' This 

 [S. lagopus] and the two following [i.e., S. bellidioides and IS. saxifragoides], 

 though most dissimilar in their usual states, appear to me to be united 

 by intermediate forms," and (Flora Novae-Zelandiae), " This and the two 

 following are closely allied and very singular species." 



The distribution of S. saxifragoides is given by Hooker as ' Port 

 Cooper " ; by Kirk as " Port Lyttelton, Banks Peninsula " ; and by Cheese- 

 man as " Port Lyttelton and other localities on Banks Peninsula." 



All agree in describing the leaf of S. saxifragoides as broader or more 

 nearly orbicular than that of S. lagopus ; but they do not quite agree as 

 to the relative size. Hooker makes the leaf of S. lagopus 2 in. to 4 in. 

 long (!) ; that of aS. saxifragoides 3 in. to 5 in. long. Kirk makes the leaf 

 of S. lagopus 1 in. to 8 in. long (excluding the petiole), and that of *S. saxi- 

 fragoides 3 in. to 6 in. long. Cheeseman makes the blade of *S. lagopus 

 1 in. to 5 in. long, and that of S. saxifragoides 3 in. to 6 in. long. Raoul's 

 description of S. lagopus (Choix, p. 21) gives the leaf about 1 decimetre 

 (4 in.) long and from 7 to 9 centimetres (3-3J in.) broad. Hooker's and 

 Raoul's descriptions would seem to have been based upon comparatively 

 small specimens of both species. 



