G. M. Thomson. — On the Origin of the New Zealand Flora. 499 



land ; 7* belong to genera which are chiefly found in Eastern Austraha, 

 from whence the species in question have probably spread themselves east 

 and west ; and 7f more are of genera of which I do not know the centre of 

 dispersion. 



A close examination of the whole leads strongly to the conclusions that 

 the basis of the floras of Eastern Australia and New Zealand are somewhat 

 identical ; that both have received immigrants independently after their 

 separation, from north and south, — Australia by reason of its northern land 

 connections with New Guinea receiving the greatest number of tropical 

 species, and New Zealand from its southern extension the greatest number 

 of antarctic and American species ; that the West Australian flora proved 

 more aggressive than the Eastern, and thus overran the whole continental 

 area, giving it its peculiarly characteristic facies ; and that of the Eastern 

 species only those having considerable powers of dispersion have succeeded 

 in spreading themselves westwards. 



In considering the geographical distribution of a flora it is usual to 

 bring under review only the phanerogamic or flowering plants, because the 

 spores of Cryptogams furnish them with a most remarkable power of dis- 

 persion by wind. Yet even the distribution of our ferns and other vascular 

 Cryptogams bears its testimony in support of the theory of the origin of the 

 flora enunciated by Mr. Wallace. Excluding the endemic species there are 

 about 30 per cent, of remaining forms which are spread extensively over a 

 great part of the globe, about 4 strictly American, another 30 of tropical, 

 Asiatic, or Polynesian occurrence, and about 36 per cent, almost exclusively 

 Australian, Of the 85 species common to New Zealand and Australia, only 

 15 occur also in West Australia, and these are all species of very wide and 

 general distribution. 



In bringing to a conclusion these somewhat disconnected remarks, I 

 shall endeavour to show how they may be pieced together so as to give 

 some idea of the present standing of the whole question. In examining 

 such a matter, some starting point or line of demarcation must be taken, 

 for were we to go far enough back we should have to account for the very 

 existence of flowering plants themselves. There are those who believe that 

 all our species have been produced by development from a few forms origin- 

 ally created in this region of the world, while others ignore the idea of 

 _ 



* 1, Vittadinia australis ; 2, Erechtites prenanthoides ; 3, Erechtites arguta ; 4, 

 Erechtites quadridentata ; 5, Pterostylis squamata ; 6, Microlana stipoides ; 7, Echino- 

 pogon ovatus. 



t 1, Poranthera microphylla ; 2, Thelymitra longifolia ; 3, Schoenus axillaris ; 4, 

 Cladium glomeratum ; 5, Cladium gunnii ; 6, Dichelaclme stipoides (Stipa teretifolia) ; 

 7, Dichelaehne crinita, 



