246 A NATURALIST IN THE PACIFIC chap. 



Accepting the antiquity of the order, and regarding it as 

 probably dating far back in geological time, he observes that the 

 evidence points to a very wide dispersion of its original stock at an 

 early period. Africa, West America, and possibly Australia, 

 possessed the order at the earliest recognisable stage. There 

 must have existed, he contends, at this early period some means of 

 reciprocal interchange of races between these regions. Then 

 followed a stoppage of communication, or a suspension of the 

 means of dispersal, between the tropical regions of the Old and 

 New Worlds ; but long after communication was broken off in the 

 warmer regions, it still existed, as he holds, between the alpine 

 heights in those regions and also between the high northern 

 latitudes of both hemispheres. Referring particularly to the 

 Hawaiian Group, he considers that the large endemic element 

 among the Compositae indicates that the ancient connection, 

 whether with America or with Australasia, has been so long 

 severed as not to have left a single unmodified common form. 

 Fitchia, the Tahitian genus, as we have already remarked, is 

 regarded as the only remnant of an ancient Composite flora in the 

 tropical islands of the South Pacific. 



In the light of these reflections it will be interesting to glance 

 at the general distribution of the shrubby and arborescent or woody 

 Compositae. Mr. Hemsley, having generally discussed the subject, 

 arrived at the conclusion that, " although they form so large a 

 proportion of the floras of St. Helena, Juan Fernandez, the 

 Sandwich Islands, and some other islands, they are not specially 

 insular." There are scores of them, he goes on to say, in South 

 America, Africa, Madagascar, India, Australia, and New Zealand 

 from twenty to forty feet high, and more truly arboreous than the 

 insular ones ; whilst nearly every sub-order has its arboreous 

 representatives. He was, however, unable to form any definite 

 opinion of the method of distribution of the woody Compositae. 

 Taking those of St. Helena and Juan Fernandez, he observes that 

 they are not more closely allied to the Compositae of the nearest 

 continents than they are to those of more distant regions. The 

 occurrence of arboreous Compositae, belonging in each case to 

 different tribes, in so many remote oceanic islands, coupled with 

 the distribution of the genera to which they bear the greatest 

 affinity, seems, he observes, to indicate that they are the remains of 

 very ancient types {Inirod. Bot. Chall. Exped., pp. 19 — 24, 66, 68 ; 

 also Parts ii. p. 61, and iii. p. 23J. 



The further discussion of this subject would lead us into a wide 



