112 Diplommatina Huttoni and Ennea bicolorin the West Indies. 
be very probably transported with living plants, or with roots 
or Me Mr. Guppy doubts whether the animals would sur- 
vive the voyage from the East to the West Indies. Of this 
there can, I think, be no question. Mr. Benson, if I am not 
mistaken, has had specimens of Diplommatina alive in Eng- 
land; and there are very few Indian shells which, when esti- 
vating, will not bear a journey of several months without in- 
jury, provided damp or excessive cold be avoided. 
That the introduction of a single pair of shells is ample for 
the diffusion of the species has been proved in Calcutta in the 
case of Achatina fulica. The facts are well known, but will 
bear repeating. About twenty-five years ago, two specimens 
were brought from Mauritius, and placed in a garden. Now 
the species abounds almost everywhere throughout an area of 
at least five miles in length. In many places several hundreds 
might be collected. Ten years ago, to my own knowledge, 
the shell was quite unknown in the Botanical Gardens on the 
opposite bank of the Hoogly. The other day I saw it living 
there in abundance. Of course, in a large city like Calcutta, 
where plants are constantly transferred from one garden to 
another at a distance, great facilities for dispersion exist; but 
the numbers, all unquestionably derived from a single pair in 
the course of so short a time, are nevertheless astonishing. I 
have very little doubt that one impregnated female would suffice 
equally well to introduce a species. 
Another fact in favour of Diplommatina Huttoni and Ennea 
bicolor having been introduced into the West Indies by man 
is, that both are very small shells, precisely such as would 
most easily escape notice and be transported with plants. No 
shell is more likely than the Hnnea to have been thus carried 
into foreign countries. ‘The case of the Diplommatina is cer- 
tainly far more difficult, but still it appears to me to present 
fewer difficulties than the theory of migration. Is there a 
botanical garden in Trinidad ? 
If the Diplommatina has not been transported artificially, I 
should be almost inclined to suspect that the Trinidad species 
is not really identical with that inhabiting the Western Tiss 
layas, but that two forms, closely resembling each other, have 
originated separately at the extreme limits of the area occupied 
by the genus. 
With regard to the Hnnea, I have very little doubt of its 
having been transported. Many of the cultivated plants of 
the West Indies must have been introduced by the Spaniards 
‘and Portuguese, some of them, in all probabil , direct from 
India; and the date of the introduction may thus have been 
sufficiently distant to allow of a considerable amount of disper- 
sion amongst the various islands. 
