386 OEIGIN OF LIFE IN AMEEICA 



moreover, is riddled with the burrows of myriads of land 

 crabs, which have aided the domestic animals, to the best of 

 their ability, in this work. Trinidad seems to have been 

 densely wooded formerly with tree ferns, palms, etc., whereas 

 living trees are now confined to the mountain tops. Among 

 the ferns collected on the island by Dr. Copeland * there was 

 one (Asplenium compressum) hitherto only observed in St. 

 Helena. Of the fauna nothing appears to be known. 



Ascension island lies in about the middle of the southern 

 Atlantic. When Darwin visited the island during his famous 

 voyage round the world, he found little there of interest. A 

 principal mound in the centre looks as if it were theparent of 

 the lesser volcanic cones studded round the island. The sur- 

 face is parched and barren, and everything presents a scene 

 of utter desolation. Yet not only is Ascension island in- 

 habited, the scanty pasture has even been made serviceable 

 for a number of sheep, goats and cows. Ascension stands on a 

 submarine bank about two hundred miles in length. It is 

 probable on that account that the existing island only repre- 

 sents the last remnant of a cluster of volcanic cones which 

 rose high above the surrounding land. The surviving fauna 

 and flora are extremely poor. Many of the species, like the 

 centipede Scolopendra morsitans, are almost cosmopolitan in 

 their range, a few also occur in Africa or South America. 

 But no effort has as yet been made to conduct a thorough 

 zoological and botanical survey of the island, and it is to be 

 hoped that this will be accomplished before all traces of the 

 ancient relicts that might still occur have been superseded 

 by recent importations. At any rate, nothing of any impor- 

 tance can be gathered from! the little information we possess.f 

 St. Helena, like Ascension island, is wholly volcanic in 

 structure, and being, moreover, surrounded by depths up to 

 17,000 feet, Dr. Wallace claims that we ought to be satisfied 

 as to its being a true oceanic island and as to its owing none of 

 its peculiarities to a former union with any continent or other 

 distant land. But, as I have pointed out once before, the exis- 

 tence of such a great depth of the ocean does not prove that it 



* Copeland, E., " Insel Trinidad," pp. 274—277. 



t Qiintlier, A., and others, " Collection made in Ascension Island." 



