DISTRIBUTION OF THE MOEE PEOMINENT NATUEAL OEDEES. 249 



Four genera are common to Africa and America only ; these are Sabicea, Bertiera, 

 Diodia, and Mitracarpum; and there are no fewer than seven endemic monotypic 

 genera. Excluding the cosmopolitan tropical genus Psychotria, the characteristic 

 genera Bondeletia and Bouvardia are the most numerous in species ; and Deppea, Hoff- 

 mannia, ffoustonia, and Crusea are other genera having their greatest development 

 within our boundaries. The Rubiaceae are one of the few dicotyledonous orders in 

 which the north-eastern extensions considerably exceed the north-western ; the numbers 

 being thirteen genera and twelve species against six genera and eight species. 



Compositce. 



In his essay on the " Classification and Distribution of the Composite " * and in 

 Bentham and Hooker's ' Genera Plantarum,' the late Mr. Bentham divided the Com- 

 positse into thirteen suborders and 766 genera ; and he estimated the species at 9800. 

 These numbers constitute 10'1 per cent, and 10*2 per cent, respectively of the genera 

 and species of all phanerogamic plants as defined and estimated in the ' Genera 

 Plantarum/ Since the date of these publications (1873) upwards of fifty new genera 

 of Composite have been proposed and described, many of them American, and founded 

 by Dr. A. Gray ; and the total may now be fairly put at 800. As to the total number 

 of species 10,000 is certainly not too high an estimate, as may be gathered from the 

 synopses of species of various parts of America: Brazil, 150 genera and 1280 species f; 

 America, north of Mexico, 221 genera and 1576 species J ; Mexico and Central America, 

 215 genera and 1518 species; Andes, genera 65, species 470 § ; and Chili about 

 1000 species ||. The last, and our own also, perhaps, may be a little too high, other- 

 wise the figures are tolerably accurate, and the aggregate of species is 5844. The 

 number of species recorded from Cuba is 184, and from the British West Indies about 

 150. The countries given do not, of course, comprise the whole of America ; but after 

 making all necessary reductions for bad species and extensions of species into two or 

 more of the areas, there would remain at least fully 5000 species for the whole of 

 America against Bentham's estimate of 4525. This will be evident from the fact that 

 less than 200 of the species in our enumeration extend north of Mexico, so that about 

 2900 species inhabit North and Central America ; 1030 of the Brazilian species are set 

 down as endemic ; and the Andine are so almost without exception. The foregoing 

 figures exclude Guiana, Venezuela, and tropical western South America, as well as 

 the region east of the Andes from Bolivia and Argentina to Patagonia, and northward 

 on the eastern side to Uruguay ; and at a low computation a thousand inhabit these 



* Journal of the Linnean Society of London, ziii. pp. 335-577. 



t Baker in ' Flora Brasiliensis,' vi. 3, p. 408. 



$ Gray, ' Synoptical Flora of N. America,' ii. 1, p. 465. 



§ "Wedaell, ' Chloris Andina,' i. 



|| Philippi, ' Catalogue Plantarum Yascularium Chilensium.' 



