Nov. 1900.] BOTANICAL SOCIETY OF EDINBURGH 3 



produce, as they ascend, clouds saturated with moisture, 

 and these, coming into contact with the colder strata of air 

 aloft, are condensed, and fall on the hills in frequent and 

 heavy showers, sometimes in torrents. It will be well, as 

 bearing closely on the subject in hand, to give some idea of 

 what the rainfall is. I will take the year from April 

 1895 to March 1896, as being the year which covers my 

 residence in the island. At Kingston, near the sea-level, 

 the rainfall was 2 2 "3 in.; at the Hope Botanic Garden, at 

 an elevation of 600 ft., it was 50'98 in.; at the Castletou 

 Eotanie Garden, nearly the same altitude, it was 108"88 

 in.; at the Hill Gardens, which lie 4900 ft. above the sea, 

 it was 122'45 in.; and on the Blue Mountain peak, at a 

 height of 7423 ft., it was 176-86 in. And though some 

 months are very much more rainy than others, there was 

 no month in which the rainfall, at least on the higher 

 grounds, was not considerable. It would seem then that 

 Jamaica possesses all the requisites necessary for the 

 luxuriant growth of such a plant as the fern — shade, 

 moisture, and a temperature which varies at different 

 elevations from heat to comparative coolness. A titter 

 home for this particular class of plants could not be 

 conceived. 



But, as a matter of fact, are ferns found there in such 

 numbers and variety as to warrant us in regarding their 

 abundance as something phenomenal ? Let us institute a 

 comparison between Jamaica and the British Isles. But 

 observe, first of all, that the area of Jamaica is only about 

 four thousand square miles, a little less, i.e., than the area 

 of Inverness-shire, including in the county the islands that 

 form part of it. Now in the whole of the British Isles 

 there are, according to the last edition of the London 

 Catalogue, only 20 genera of ferns, containing 47 species, 

 and of these genera, 1 1 have only 1 species apiece. In 

 Jamaica, on the other hand, there are, according to the 

 most recent authority, Mr. Jenraan, of Demerara, no fewer 

 than 45 genera, with 473 species — all within ihat small 

 area, about equal in size to Inverness-shire — more than 

 ten times as many as occur in the whole of Great 

 Britain and Ireland. Many of the genera too are very 

 rich in species. The genus Cyathea has 16 specit-s, Pteris 



