450 Journal of the Asiatic Society of Bengal. [N.S., XIV, 
specimen, and further corroborates the accuracy of the habitat 
of the Maskat specimens, whose attribution to that locality 
cannot be referred to any error of labelling. 
There is no doubt, therefore, that Doliwm variegatum does 
really live in the northern part of the Arabian Sea. 
The specimens of Dolium variegatum both from Maskat 
and from Karachi are in every way similar to those from 
Australia. 
We may take it as an established fact that, at the present 
day, the species does not exist along the coasts of peninsular 
India or in the Malay Archipelago, as these regions have been 
sufficiently explored to dispose of the likelihood of such a 
conspicuous shell being overlooked. We have here, therefore, 
a remarkable instance of a species with a totally discontinuous 
distribution at the present day, while we possess direct 
appearance of a particular species in one particular locality and 
, 
t appeara p d 
to others. Nevertheless, judging from available data, the 
] e 
of geological sequence. It would seem as though the spread of 
@ Species, in former geological times, is comparab 
organised plants or animals, when introduced accidentally of 
i an incredibl 
ime 
whole continents, the invasion often assuming the character 
a veritable “ pest.’’ 
_ Geology, in some instances, may supply 
origin of certain great natural groups in a particul 
implying the idea of migration on a large scale was that 
colonies,” that is of groups of species especially charac 
Maskat”’ is written in ink on the specimens, 
not on 
! The name « 
detached labels. 
