232 REMARKS ON CONCHOLOGY AND MALACHOLOGY* 
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 Her¬ 
mit 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 pa¬ 
rallel instance of the effect of artificial life upon some of the low¬ 
er 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 arc so mi¬ 
nute that their forms are not 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 spe¬ 
cies 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 exten¬ 
sive plain, having a 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 shewn by the salt water penetrating for miles into 
the interior of the island, and, at spring tides, even overflowing cul¬ 
tivated fields. Over some parts of this low ground there is a layer of 
decomposed 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 are com¬ 
mon in open sandy bays or straits. After a careful examination, I 
cannot pronounce any to be different from those found in the ad¬ 
jacent seas 5 the forms of most of them are perfect, and in a few the 
colour is preserved, but they have for the most part lost their 
hardness, being readily crushed between the fingers. The kinds most 
abundant are as follows,—Placenta plactma, Strombus incisns, S. la- 
biosus, several species of Nassa, Columbella, Trochus, Cerithium, 
Mitra, Turritella. Dentalium Aspergillum, Area, Venus, Corbula. Tel- 
