102 St. Helena. 



PAET I. 



respects a very singular one ; it was classed, even by 

 Lamarck, in a marine genus, and having thus been 

 mistaken for a sea-shell, and the smaller accompanying 

 species having been overlooked, the exact localities 

 where it was found have been measured, and the eleva- 

 tion of this island thus deduced ! It is very remarkable 

 that all the shells of this species found by me in one 

 spot, form a distinct variety, as described by Mr. 

 Sowerby, from those procured from another locality by 

 Mr. Seale. As this Cochloo-ena is a large and con- 

 spicuous shell, I particularly enquired from several 

 intelligent countrymen whether they had ever seen it 

 alive ; they all assured me that they had not, and they 

 would not even believe that it was a land animal : Mr. 

 Seale, moreover, who was a collector of shells all his 

 life at St. Helena, never met with it alive. Possibly 

 some of the smaller species may turn out to be yet 

 living kinds ; but, on the other hand, the two land-shells 

 which are now living on the island in great numbers, 

 do not occur embedded, as far as it is yet known, with 

 the extinct species. I have shown in my Journal, 1 that 

 the extinction of these land-shells possibly may not be 

 an ancient event ; as a great change took place in the 

 state of the island about 120 years ago, when the old 

 trees died, and were not replaced by young ones, these 

 being destroyed by the goats and hogs, which had run 

 wild in numbers, from the year 1502. Mr. Seale states, 

 that on Flagstaff Hill, where we have seen that the 

 embedded land-shells are especially numerous, traces 

 are everywhere discoverable, which plainly indicate 

 that it was once thickly clothed with trees ; at present 

 not even a bush grows there. The thick bed of black 

 vegetable mould which covers the shell-bed, on the 



1 * Journal of Kesearches,' 1845, p. 489. 



