454 
THE GEOLOGIST. 
readable. It bet^ins with an iutrodtictory cliaptci- in Forbes' own easy polished 
style, ill which the general distribution of organic life into distinct botanical 
and zoological provinces of greater or less extent, according to theii- degree of 
limitation by physical or climntaJ conditions, is succinctly pointed out. Tliese 
provinces are not so entirely dist inet, each from its neighbour, but that some com- 
mingling of tlie characteristic life-forms take place in the boundary regions 
which infringe upon eacli other. These provinces, as understood in this work, 
are areas " witliin whieli there is evidence of the special manifestation of the 
Creative Power ; that is to s;iy, within which there have been called into being 
the originals, or protoplasts, of aniinals or plants." 
The aborigines of tlicse areas in the lapse of time, or through the altered 
geogra})liical and pliysieal conditions of our planet, may become mixed up with 
emigrants from otlicr provinces, and even exceeded by them in numbers. The 
distinguishing, tlicreforc, of the original types and the determination of the 
causes which have produced and direct cd the invasion, are among the problems 
wliich the investigator of the distribution of animated creatures has to endeavour 
to solve. In the investigation of the fauna or flora of a province " the diffusion 
of the individuals of the characteristic species is found to indicate that the 
manifestation of the creative energy has not been equal in all parts of the area, 
but that in some portion of it, tliat usually more or less central, the genesis of 
new beings has oeeu more intensely exerted than elsewlicre. Hence, to re- 
present a province diagrammaticaUy, we might colour a nebulous space, in 
wliich the intensity of the hue would be exhibited towards the centre, and be- 
come fainter and fainter towards the circumference." This feature of zoological 
and botanical provinces gives rise to the term " centres of creation" which 
Forbes and otlicrs have applied to them. Nowhere do we find a province re- 
peated, or, in other words, "no species has been called forth originally in more 
areas than one. Similar species, to which the term representative is mutually 
applied, appear in areas distant from each other, but under the influence of 
smidar physical conditions." The term specific centre has been employed to ex- 
press the point upon wliich each species had its origin, and whence its incbvi- 
duals have spread and radiated. In the course of its diffusion, or during 
the lapse of time, a species may become extinguished in its original centre, 
and groups of individuals may tluis become isolated at spots far distant from 
each otlier. Indeed, the true specific centre in some cases may be rightly 
placed in the rock-strata of tlic earth, involving the necessity of tracing the 
history of the species backward in time, and of investigating its connection 
with geological changes. 
Provinces also, like species, must be traced back to their liistory and origin in 
past time ; for paleeontologieal research exhibits the phenomenon of provinces in 
time, as well as provinces in space. Species, moreover, have a centering in geo- 
logical time as well as in geographical space, and no species are repeated in time, 
that is, there has been no recreation of any same specific form ; wlule " the distri- 
bution of the individuals of fossO. species also mdicates their diffusion from 
some unique point of origin, and consequently goes to support the notion of the 
connection of these individuals thi-ough the relationship of descent, and the 
derivation of them all from an original protoplast." 
The sea-board of Europe extends through four degrees of latitude and six of 
longitude, from within the Arctic Circle to tlie Pillars of Hercides, with a last 
and isolated portion constituting the north-west border of the Caspian Sea. 
Along such a range of shore, extending through various climates, from the 
warm and sunny confines of Africa to the ice-bound cUffs of Nova Zcnibla and 
Spitzbergen, there are many and diversified assemblages of animated creatiu'es. 
Those which " delight in the chilly waters of the Arctic Ocean must be very 
different from those which revel in the genial seas of the south ; wlulst the 
