TEOPICAL FLOEAS 67 



Nicaragua, Costa Kica, and Panama (3000 species) 



1. Orchidcai 280 



2. Conipositu? 107 



o. LegLiiniiiQsaj 17(3 



4. Riibiaeete 14(5 



5. Uraminetp iH) 



6. Eiiphoibiacese 72 



7. Gesneraceaj GO 



8. Cyperawa? 08 



0. Alelastomacea^ 07 



10. Urticacoai 58 



11. Aioideie 5-t 



12. Palraai 50 



Ferns 252 



This table brings out clearly the extra-tropical character of 

 Mexico as compared with these tro|)ical sections of Central 

 America. Xo less than five orders of the former twelve have to 

 be omitted (Cactacea?, Labiates, Solanacese, Piperaceas, and Mal- 

 vaceae), which are replaced by the more exclusively tropical Ges- 

 neracea?, Melastomacese, Urticacese, xVroideae, and Palmte. 

 Here, in two adjacent areas differing about 12° in mean lati- 

 tude, there is a more pronounced difference in the prevalent 

 orders of plants than exists between two great regions on oppo- 

 site sides of the globe. Another characteristic tropical feature 

 is seen in the large number of ferns, which are nearly one- 

 half those of the whole number found in Mexico and Central 

 America, which has an area nine times as great. 



Of the other tropical American floras little need be said. 

 Jamaica and Trinidad are the onlv West Indian islands of 

 the larger group for which I have been able to get recent 

 figures. Mr. L. ]^. Brittan, of the ]^ew York Botanical Gar- 

 dens, who has collected in the former island, estimates the 

 species at 2722, which, for a sub-oceanic island, is a large 

 amount. Trinidad, which is almost a part of the continent, 

 should be much richer, and its existing collections, not quite 

 reaching 2000, are certainly much below its actual number 

 of species. The Galapagos, now probably fairly well known, 

 but possessing only 445 species, show us how scanty may be 

 the flora of a group of islands of considerable size and situated 

 on the equator, when the conditions are not favourable for 

 plant-immigration or for the gTowth of plants at or near the 

 sea-level, as has been pointed out in my Island Life. 



