66 
(1) the Eastern United States and Eastern Asia, (2) the flora 
of the West African rain forest with that of the eastern coast of 
Brazil, (3) the Mascarene flora and that of Southern India, (4) the 
South African and West Australian floras, (5) the New Zealand 
and South West American floras, and nearer home (6) the South 
West British and Lusitanian floras. 
Whether these areas were at one time connected by intervening 
land bridges, where now are deep oceans, or whether they were 
actually once contiguous areas which have now become separated 
will for long remain a debatable question. Certainly the com- 
paratively new theory* of the origin of continents, 7.e., by 
displacement and gradual divergence one from another, would 
easily explain many of the problems of plant distribution. 
Though this subject cannot be fully dealt with here, it seems 
significant that with few exceptions these floral affinities of 
_ distant areas are entirely in an east and west direction and hardly 
ever north and south. I disregard for the moment the supposed. 
affinity between the Mediterranean and South African floras 
which may be due to parallel evolution in the two hemispheres. 
The distribution of the filmy fern, Hymenophyllum ferrugineum, 
of Juan Fernandez, Chile and New Zealand, cannot easily be 
explained otherwise than by a former land connection, especially 
when we consider also the distribution} of Galaxias attenuata, 
a fresh-water fish, which occurs in South East Australia, 
Tasmania, New Zealand and subantarctic South America. I merely 
quote these examples from among a multitude of others to show 
that the phylogeny of plants is intimately connected with many 
interesting biological problems and should not be neglected, 
and a phylogenetic system of classification should be the ultimate 
aim of RORY In fact the description of every new genus, 
every new species or form of plant may be regarded : as a 
nat a towards this end. 
SYSTEMS OF CLASSIFICATION. 
The number of systems of classification is now very consider- 
able. For an excellent account of the earlier systems the reader 
is referred to Lindley’s “ Vegetable Kingdom ” (introduction), 
and for later schemes to Rendle’s ‘“ Classification of Flowering 
Plants ” (vol. 1, Historical Introduction). Since Lindley’s time, 
however, only two great treatises have appeared which have 
commanded universal attention, namely, the “ Genera Plantarum” 
of Bentham and Hooker, published in 1862-1883, which elaborated 
the De Candolle System, and the “* Natiirliche Pflanzenfamilien 
of Engler and Prantl (1887-1909). From a phylogenetic stand- 
point both these works have been subjected to a considerable 
amount of criticism, especially that of Bentham and Hooker. er. 
* See Welgeabi “The Origin of Continents and Oceans,” in 
Discovery iil, 114-118, figs. 1-3 (1922). 
t See Coc ckayne ‘ ‘The Vegetation of New Zealand,” in scale & Tune, 
“Die Veg. der Erde,” 14: 326 (1921). 
