NATURAL AREAS AND REGIONS 



651 



interspersed with thickets and isolated 

 trees of various trees and taller shrubs, 

 among which Byrsonima is especially 

 abundant. 



The high mountains of the Pakaraima 

 range maintain a forest similar to that 

 of the low country in general aspect, but 

 with many additional species. In our 

 present state of knowledge, it is impos- 

 sible to name the most typical genera 

 or species, and endemics are abundant. 

 The same vegetation probably extends 

 westward along these mountains across 

 southern Venezuela as far as the Orinoco. 



The highest mountains, Roraima and 

 Kukenaam, have long been known for 

 their remarkable endemism, amounting 

 to about 40% of the known species, and 

 their flora shows some resemblance to 

 that of the Andean region. 



6. One-quarter sq. mi. of jungle at 

 Kartabo 1 (W.B.) 



Geographical position 



Kartabo, the site of the Tropical 

 Research Station of the New York 

 Zoological Society, is situated in the 

 north-central part of British Guiana, 

 South America, at the junction of the 

 Mazaruni and Cuyuni Rivers, 6 mi. 

 above where these combined streams 

 enter the still larger Essequibo River. 

 Its position on the earth's surface is 

 58 42' W. longitude and 6 23' N. lati- 

 tude, approximately 400 mi. from the 

 equator and 45 mi. from the Atlantic 

 Ocean. 



Nine-tenths of the general work has 

 been carried on within an area of 2000 

 by 4000 ft. This area is included in the 

 easterly portion of the black area shown 

 on the accompanying map. Unless 

 otherwise stated, the following account 

 of the general ecology of this region, 

 and the various articles which will 

 follow in future numbers of Zoologica, 

 dealing with more definite, intensive 

 researches, refer altogether to this tract 

 of land and water, measuring 2000 by 



1 This paper presents a few aspects of the general 

 paper on the subject which will appear in "Zoo- 

 logica," the scientific journal of the New York 

 Zoological Society. 



4000 ft., at the very point of juncture 

 of the Cuyuni and the Mazaruni Rivers 

 an area less than one-quarter the size 

 of Central Park in New York City. 



Meteorological conditions 



Accurate records of weather con- 

 ditions have been taken at the Cli- 

 matological Station at His Majesty's 

 Penal Settlement, 3 mi. below Kartabo. 

 The statements given here are based 

 upon the published and unpublished 

 records of this Station which extend 

 over a period of twenty years. 



Seasons. Four seasons are recognized 

 in Guiana a short and a long dry, and 

 a short and a long wet season. The 

 following table shows the generally 

 accepted seasonal grouping of months, 

 although slight variations from this 

 table are constantly apparent. 



Short dry season: February, March, 



April. 



Long wet season: May, June, July. 

 Long dry season: August, September, 



October, November. 

 Short wet season: December, January. 



During the months allotted to the 

 rainy season approximately 58% of the 

 rains fall, the precipitation amounting 

 to an average of 11.73 in. per month. 

 During the dry season 42% of the yearly 

 rainfall is felt, the monthly average 

 being 6.04 inches. 



Rainfall. The average rainfall is 

 100.53 in. per year, the heaviest rainfall 

 being in May (14.00 in.) followed by 

 June (12.44 in.) and July (12.40 in.). 

 March has the lowest rainfall with but 

 4.94 in. to its credit. The highest 

 records for annual rainfall is 117.75 

 in. (1918) and the lowest 77.11 (1911). 

 Rain falls on an average of 219 days a 

 year. The highest rainfall for a single 

 month was in May, 1918 (22.34 in.) 

 and the lowest in February 1912 (0.03 

 in.). 



Humidity. The yearly average for 

 humidity is 84.2%. The daily averages 

 are as follows. 



7a.m.. 90.9% 



1 p.m 79.0% 



6 p.m 82.2% 



