124 DISEASES OF CROP-PLANTS 



a width of about ii miles and the largest channel from the north 

 a width of only 8 miles. 



The island is traversed by three ranges of hills running 

 approximately east and west. Only the elevations of the 

 Northern Range, which lies immediately behind the north coast, 

 have the character of mountains and rise to a maximum height 

 of 3,000 feet. This range is an obvious continuation of a similar 

 range in Venezuela, and is connected with it by the promontories 

 and rocky islands which form the northern boundary of the Gulf 

 of Paria. The Southern Range of low and broadly scattered 

 hills occupies a somewhat similar position relative to the south 

 coast, while the Central Range, made up of hills mostly well below 

 1,000 feet, runs about midway across the island. Between the 

 ranges lie the Northern Plain, an unbroken alluvial flat drained 

 by the River Caroni, and the Southern Plain, which is dissected 

 into shallow troughs and ridges. 



From the physical and biological points of view Trinidad 

 must be regarded rather as a detached part of South America 

 than as a member of the Antillean Chain, and its structure clearly 

 indicates a history in which it has formed part of the continent 

 and has been traversed by an outlet of what is now the Orinoco 

 River. 



The average annual rainfall is about 64 inches. The dry 

 season extends from January to the middle of May with an aver- 

 age precipitation of about 3 inches per month. From June to 

 November there is an average fall of about 8 inches per month. 

 As regards distribution within the island there is a distinct 

 reduction from east to west ; the line separating the area with 

 50-75 inches from that with 75-100 inches almost bisects the 

 main body of the island from north to south. 



There are a few small areas in the north-east with recorded 

 averages over 100 inches, while the north-western peninsula and 

 its islands fall below 50 inches. 



A great part of the island being covered with forest or with 

 almost equivalent cacao cultivations, the climate is distinctly 

 humid and very favourable to the development of a rich vegeta- 

 tion, much more so than the recorded rainfall would suggest. 



The most important agricultural industry of the island is the 

 growing of cacao, of which the production amounts at present 

 in an average year to about 27,000 tons. The crop next in im- 

 portance is sugar-cane, from which an annual output of roughly 

 50,000 tons of sugar is obtained. The area under coconuts has 

 been rapidly extended in recent years, and the present production 

 is in the neighbourhood of 25 million nuts per annum. In the 

 minor industries rice is grown for local consumption to the extent 

 of about 2,500 tons and there is a considerable production for 

 local use of Indian corn, peas and beans, cassava, yams, sweet 

 potatoes, dasheens, tannias, eddoes, bananas, mangoes and 

 oranges. The supply of these foods is more than adequate in 



