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Show 308 ISLAND LIFE. [PART II. article was written. The most remarkable feature here is the great abundance of Lobeliacere, a character of the flora which is probably unique; while the superiority of Labiatre to Leguminosre and the scarcity of Rosacere and Orchidacere are also very unusual. Composites, as in most temperate floraA, stand at the head of the list, and as these have been carefully studied by Mr. Bentham, it will be interesting to note the affinities which they indicate. Omitting four genera and species which are cosmopolitan, and have no doubt entered with civilised man, there remain twelve genera and forty-four species of Compositre in the islands. All the species are peculiar, as are six of the genera ; and in another genus, Coreopsis, the· six species form a peculiar named section or subgenus, Campylotheca; while the genus Lipochreta with ten species is only known elsewhere in the Galapagos, where a single species occurs. We may therefore consider that eight out of the twelve genera of Hawaiian Compositre are really confined to the Archipelago. The relations of the genera are thuR given by Mr. Bentham:- No of Species. Lagcnophora 1 Aster 1 'l'etramolobium 6 Vittadinia 1 Campylotheca (s.g) 6 Bidens 1 Lipochrota 10 Argyroxiphium 2 Wilkesia 1 Dubantia 3 Raillardia 11 Hesperomannia 1 Ex:ternnl Relations of the Species. With the Old World and Extra-Tropical America. American and Extra-Tropical Old World. South Extra-Tropical American. South Extra-Tropical American and Australian. With the Tropical American and very few Old World species of Coreopsis and Bidens. The Tropical American species. American W edelioidro and Helianthioidro. With Madiere of the Mexican region. With Madiere of the Mexican region. Distantly with Madieru and Ga1insogere of the Mexican region. With Raillardella of the Mexican region. With Sti.fftia and Wunderlichia of the Brazilian reg-ion. ~he great preponderance of American relations of the Oompo~ Itre, as above indicated, is very interesting and suggestive. It IS here that we meet with some of the most isolated andremarkabl~ forms, implying great antiquity; and when we consider the enormous extent and world-wide distribution of this order CHAP. XV.] THE SANDWICH ISLANDS. 309 (comprising about ten thousand species), its distinctness from all others, the great specialisation of its flowers to attract insects, and of its seeds for dispersal by wind and other means, we can hardly doubt that its origin dates back to a very remote epoch. We may therefore look upon the Compositm as representing the most ancient portion of the existing flora of the Sandwich Islands, carrying us back to a very remote period when the facilities for communication with America were greater than they are now. This may be indicated by the two deep submarine banks in the North Pacific, between the Sandwich Islands and San Francisco, which, from an ocean floor nea~ly 3,000 fathoms deep, rise up to within a few hundred fathoms of the surface, and seem to indicate the subsidence of two islands, each about as brge as Hawaii. The plants of North Temperate affinity ma.y be nearly as old, but these may have been derived from Northern Asia by way of Japan and the extensive line of shoals which run north-westward from the Sandwich Islands, as shown on our map. Those which exhibit Polynesian or Australian affinities, consisting for the most part of less highly modified species usually of the same genera, may have had their origin at a later, though still somewhat remote period, when large islands, indicated by the extensive shoals to the south and south-west, offered facilities for the tmnsmission of plants from the tropical portions of the Pacific Ocean. Antiquity of the Hawaiian Fauna and Flora.-The great antiquity implied by the peculiarities of the fauna and flora, no less than by the geographical conditions and surroundings, of this group, will enable us to account for another peculiarity of its florathe absence of so many families found in other Pacific Islands. For the earliest immigrants would soon occupy much of the surface, and become specially modified in accordance ·with the conditions of the locality, and these would serve as a barrier against the intrusion of many forms which at a later period spread over Polynesia. The extreme remoteness of the islands, and the probability that they have alwa.ys been more isolated than those of the Central Pacific, would a.lso necessarily result in an imperfect and fragmentary representation of the flora of surrounding lands. |