The Journal of the Indian Archipelago. 267 



This artificial mode of subsistence is possibly one cause of their 

 variable form and size, as it is well-known that domestic animals, 

 and others that are more or less dependent on man for their support, 

 are very apt to produce a progeny differing more or less from the 

 parent stock. A good example of the propagation of an accidental 

 variety, must be familiar to my readers in the instance of a well- 

 known domestic animal of the feline genus, which in Singapore is 

 rarely seen with a perfect tail. In the neighbourhood of the fish 

 markets may also be seen multitudes of dead shells of all sizes, 

 some so minute as to be microscopic, and all tenanted by Pagurii or 

 hermit crabs, as varied in size as the shells they inhabit, and like 

 the Nassa, busily engaged in devouring fragments of dead fish, 

 which is their principal food. I make mention of them here as a 

 parallel instance of the effect of artificial life upon some of the lower 

 animals, for these crabs are not, as might be supposed, one, or at 

 most two or three, species in different stages of growth. If an 

 examination be made, it will be found that individuals of all sizes are 

 laden with spawn, not excepting such as are so minute that their 

 forms are not to be distinguished by the naked eye : it cannot be 

 imagined that each of these is a different species, they are in fact an 

 evident instance of the alteration of a species into an almost infinite 

 number of varieties. 



" Of the various localities in which the Singapore shells are found, 

 one remains to be mentioned, to describe which intelligibly, I must 

 briefly advert to the general form of the island of Singapore. It 

 consists of a cluster of low undulating hills, based on an extensive 

 plain, having an uniform level surface, in some places not varying 

 above two or three feet, in an area of several square miles. The 

 whole of this valley ground is but little raised above the level of the 

 sea, as is shown by the salt-water penetrating for miles into the 

 interior of the island, and, at spring-tides, even overflowing cultivated 

 fields. Over some parts of this low ground there is a layer of de- 

 composed vegetable matter of variable depth, but for the most part 

 the surface is sand, beneath which, at depths varying from 5 to 50 

 feet, there is a dark-blue plastic clay abounding in shells, and these 

 not of the kinds found in Mangrove swamps, but such as arc common 

 in open sandy bays or straits. After a careful examination, I cannot 



