404 
ZOOLOGICAL GEOGRAPHY 
[part nr. 
“ New Zealand plants are remarkably scentless, both in regard to 
the rarity of scented flowers, of leaves with immersed glands 
containing essential oils, and of glandular hairs.” There are a 
few exceptional cases, but these seem even more rare than might 
be expected, so that the confirmation of theory is very complete. 
The circumstance that aromatic leaves are also very scarce, sug- 
gests the idea that these, too, serve as an attraction to insects. 
Aromatic plants abound most in arid countries, and on Alpine 
heights ; both localities where winged insects are comparatively 
scarce, and where it may be necessary to attract them in every 
possible way. Dr. Hooker also informs, me that since his Intro- 
duction to the New Zealand Flora was written, many plants with 
handsome flowers have been discovered, especially among the 
Ranunculi , shrubby Veronicas, and herbaceous Composite. The 
two former, however, are genera of wide range, which may have 
originated in New Zealand by the introduction of plants with 
handsome flowers, which the few indigenous insects would be 
attracted by, and thus prevent the loss of their gay corollas ; so 
that these discoveries will not much affect the general character 
of the flora, and its very curious bearing on the past history of 
the islands through the relations of flowers and insects. 
In judging of the relation here supposed to exist, it must be 
remembered, that if the New Zealand insects have been int. - 
duced from the surrounding countries by chance immigrations at 
distant intervals, then, as we go back into the past the insect 
fauna will become poorer and poorer, and still more inadequate 
than at present to lead to the development of attractive flowers 
and odours. This quite harmonizes with the fact of the ancient 
indigenous flora being so remarkably scentless and inconspi- 
cuous, while a few of the more recently introduced genera of 
plants have retained their floral attractions. 
Concluding Remarks on the Early History of the Australian 
Region. 
We have already discussed in some detail, the various relations 
of the Australian sub-regions to the surrounding Regions, and the 
geographical changes that appear to have taken place. A very 
