EXCESSIVE DISCONTINUITY. 197 
Pittosporum obcordatum, originally discovered by Raoul near 
Akaroa, is a low tree, with distinct juvenile and adult forms (fig. 96). 
It has been recorded only from near Akaroa (Banks Peninsula) and 
from near Kaitaia (northern Auckland). It is probably extinct at 
Akaroa, the forest near that town, and, indeed, on most of Banks 
Peninsula, being now destroyed, and at Kaitaia there are only one 
or two trees. No tree in the world can be rarer! The seeds of 
Pittosporum are not suitable either for wind carriage or bird carriage. 
One may conclude, then, that this species was once of continuous 
distribution, but that it has been exterminated by more vigorous 
competitors. Celmisia Travers is so common on certain mountains 
of the North-western Botanical District, and of the North-eastern 
Botanical District near its western boundary, that no one caring for 
plants could fail to notice one so striking. Farther south it is absent 
until it appears again many miles away in the Fiord Botanical 
District, on the mountains near Lake Hauroko, where it was dis- 
covered by Mr. J. Crosby Smith. This species is suitable for 
wide dispersion by wind. There must be hundreds of stations 
along the western Southern Alps where it could thrive, and yet 
it is absent. The explanation that it has had a more continuous 
distribution and been exterminated cannot well meet this case; nor 
does one like to suggest that the species may have arisen in both 
localities. Puttosporum patulum is a fairly common small tree in 
southern-beech forest in certain parts of the North-western Botanical 
District. Elsewhere it is found only near Lake Hawea, where it is 
confined to the same class of forest. This may perhaps be explained 
on the theory of its being gradually exterminated, or it may be that 
the class of forest it affects had at one time a much more continuous 
distribution than is now the case. Ranunculus crithmifolius is a rare 
shingle-slip plant of the alpine belt of the North-eastern Botanical 
District. Its only other known habitat is on shingle-slip on the 
Mount Arrowsmith Range, Canterbury, where it was discovered some 
years ago by Mr. R. M. Laing. One can readily expect shingle- 
slip species to have a precarious existence, so this seems a fairly good 
example of a species once fairly widespread being now at the verge 
of extinction. Cotula filiformis until a year or two ago had been 
seen by no living New Zealand botanist, though it was known that 
Haast collected it on the Canterbury Plain. Thanks, however, to its 
rediscovery by Mr. C. E. Christensen, it has since proved to be fairly 
