516 



CHARLES DARWIN 



and twenty years had elapsed : for the goats were introduced 

 in 1502, and in 1724 it is said "the old trees had mostly 

 fallen." There can be little doubt that this great change in 



e vegetation affected not only the land-shells, causing eight 

 species to become extinct, but likewise a multitude of insects. 



St. Helena, situated so remote from any continent, in the 

 midst of a great ocean, and possessing a unique Flora, ex- 

 cites our curiosity. The eight land-shells, though now extinct, 

 and one living Succinea, are peculiar species found nowhere 

 else. Mr. Cuming, however, informs me that an English 

 Helix is common here, its eggs no doubt having been im- 

 ported in some of the many introduced plants. Mr. Cuming 

 collected on the coast sixteen species of sea-shells, of which 

 seven, as far as he knows, are confined to this island. Birds 

 and insects, 4 as might have been expected, are very few in 

 number ; indeed I believe all the birds have been introduced 

 within late years. Partridges and pheasants are tolerably 

 abundant; the island is much too English not to be subject 

 to strict game-laws. I was told of a more unjust sacrifice to 



* Among these few insects, I was surprised to find a small Aphodius 

 (nov. spec.) and an Oryctes, both extremely numerous under dung. When 

 the island was discovered it certainly possessed no quadruped, excepting 

 perhaps a mouse: it becomes, therefore, a difficult point to ascertain, 

 whether these stercovorous insects have since been imported by accident, 

 or if aborigines, on what food they formerly subsisted. On the banks of 

 the Plata, where, from the vast number of cattle and horses, the fine plains 

 of turf are richly manured, it is vain to seek the many kinds of dung- 

 feeding beetles, which occur so abundantly in Europe. I observed only an 

 Oryctes (the insects of this genus in Europe generally^ feed on decayed 

 vegetable matter) and two species of Phansus, common in such situations. 

 On the opposite side of the Cordillera in Chiloe, another species of Pha- 

 nseus is exceedingly abundant, and it buries the dung of the cattle in large 

 earthen balls beneath the ground. There is reason to believe that the 

 genus Phanaeus, before the introduction of cattle, acted as scavengers to 

 man. In Europe, beetles, which find support in the matter which has 

 already contributed towards the life of other and larger animals, are so 

 numerous that there must be considerably more than one hundred different 

 species. Considering this, and observing what a quantity of food of this 

 kind is lost on the plains of La Plata, I imagined I saw an instance where 

 man had disturbed that chain, by which so many animals are linked 

 together in their native country. In Van Diemen's Land, however, I 

 found four species of Onthophagus, two of Aphodius, and one of a third 

 genus, very abundantly under the dung of cows; yet these latter animals 

 had been then introduced only thirty-three years. Previously to that time 

 the kangaroo and some other small animals were the only quadrupeds; and 

 their dung is of a very different quality from that of their successors intro- 

 duced by man. In England the greater number of stercovorous beetles 

 are confined in their appetites; that is, they do not depend indifferently 

 on any quadruped for the means of subsistence. The change, therefore, 

 in habits which must have taken place in Van Diemen's Land is highly 

 remarkable. I am indebted to the Rev. F. W. Hope, who, I hope, will 

 permit me to call him my master in Entomology, for giving me the names 

 of the foregoing insects. 



