Spiders from the Bahama Islands. 323 
Should this paper fall into the hands of anyone interested 
in the natural history of their surroundings, situated in any 
of the islands of the Antilles, I would like to urge that 
collections, however small, are always valuable when brought 
from adjacent islands forming a large group, more especially 
if a number of examples of the commoner and more obvious 
forms be sent also. 
In this way alone can we determine the identity of the 
many forms which have been described from different islands 
as distinct species; and by securing sufficient material we 
may be able to trace the gradual transition of a species 
through successive islands until it passes into some extreme 
form which has hitherto perhaps been regarded as a distinct 
species. 
Given a sufficient lapse of time, each island may produce, 
from the same original form common to the whole district 
before its separation into groups of isolated islands, a species, 
or at all events a local race, peculiar to itself, diverging under 
different conditions, prevented by physical obstacles from 
interbreeding with those of neighbouring islands, and thus at 
last perhaps becoming a true species, physiologically distinct 
as well as geographically separated ; for in dealing with forms 
in which the male and female are each highly specialized 
individuals of different sexes the distinctness of two species 
must depend on whether they will cross-breed or not normally, 
as a rule, under natural conditions of life. If they interbreed 
freely they cannot be distinct species, while if they interbreed 
occasionally, but not as a general rule, the two forms may be 
gradually becoming divergent, and finally become physio- 
logically distinct. 
A variety is held to be an individual variation of either sex 
where these sexes interbreed freely. A local race is composed 
of individuals all of whose members differ slightly but con- 
stantly from those of apparently the same species in another 
locality more or less isolated from the first. The question as 
to what is a species, a local race, and a variety is impossible 
to settle definitely so long as the natural process of the sepa- 
rating into groups and the elimination of intermediates is in 
progress. 
Thus it is of very great interest to learn how far forms 
which have probably been geographically separated for 
centuries have passed through the stage of individual variation, 
have reached the status of local races, or have already become 
physiologically distinct species. 
‘he conditions for the observation of these phenomena 
ought to be exceedingly favourable throughout the numerous 
