42 A NATURALIST ON THE "CHALLENGER." 



less broken by low bills surrounded by a range of nigh land. 

 The low central district is evidently the bottom of an ancient 

 crater, of the wall of which the high surrounding range is the 

 remains. The range is composed of strata dipping outwards 

 from the ancient centre of eruption. It is cut up by a series of deep 

 valleys having a general radiate arrangement, into ridges of 

 various heights, which are again cut up by secondary transverse 

 valleys so as to culminate in a series of irregular peaks. 



Some of the ridges are of considerable altitude. The Green 

 Mountain is 2,483 feet in height, and one other mountain to 

 the extreme south of the island, 2,218 feet. A break in the 

 encircling range to the north-west forms the harbour or Porto 

 Grande, in the entrance to which lies a small island, called Bird 

 Eock, a fragment of the range, once continuous in this direction. 



More barren and desolate-looking spots than St. Antonio and 

 St. Vincent appear as approached from seawards, after they have 

 been suffering from their usual prolonged droughts, it is im- 

 possible to conceive of. Their general aspect reminded me of 

 that of Aden or of some of the volcanic islands in the Eed Sea. 

 At the time of our visit, no rain had fallen for a year at 

 St. Vincent. Sometimes it does not rain for three years. 



The mountains are of black volcanic rock terminating seawards 

 in precipices, in which the numerous dikes, which traverse them 

 in all directions, stand out conspicuously, often projecting far 

 through weathering of the matrix. Between the hill ranges, 

 stretches a flat sandy plain covered with sand dunes and with 

 ranges of low rounded hills of a bright red ochre tint. The 

 white sandy plain terminates at the head of the harbour in a 

 sandy shore, where is a miserable town, composed mostly of 

 mere hovels, and a black coaling jetty. 



The whole was glaring in a fierce sun, and appeared almost 

 devoid of vegetation, but from the anchorage some black tufts 

 could be made out with a telescope, which consisted of small 

 bushes of lavender (Lavandula rotundifolia) , the most abundant 

 plant in the island, and on the summits of the higher hills a few 

 Euphorbia bushes (U. tuckcyana) could be made out in the same 

 way. On the sandy plain at one spot is a thick growth of low 

 tamarisk bushes which stretches from the shore inland, amongst. 



