60 Bibliographical Notice. 
arguments advanced by Mr. Watson; and it must be allowed that 
many of the theories advocated by other writers besides Forbes rest 
too much upon negative evidence: this is especially true where use 
has been made of geological data. Perhaps it may be wiser to adopt 
the course recommended in the ‘ Cybele,’ to postpone for a while our 
inquiries into the origin and age of species, and to collect hopefully 
the materials for the future edifice, rather than attempt to rear it 
upon an insecure foundation. 
What we read in this volume of the distribution of the British 
flora is no bad example of the different groups into which the plants 
of a country may be subdivided according to individual fancy. 
Forbes saw five main groups, which he considered distinct in age as 
well as in character. Henfrey gives four, without touching upon the 
question of age. Watson has six “types,” with a seventh to be 
added for the West Irish plants; and it also appears that the writer 
who acknowledges the greatest number of groups is the one who is 
least inclined to grant a distinctness in age. 
Now, leaving out of question the alpine species, the actual features 
of the British flora are not very different from what might have been 
expected if the entire lowland vegetation were of uniform age. If we 
have upon our western shores many of the local and characteristic 
plants, is not the climate of the west coast quite exceptional as regards 
Europe? If the so-called ‘ Iberian” plants of the west of Ireland 
were originally western species, peculiar to the outskirts of their 
continent, would not the wasting of the land leave just such charac- 
ters as we now find? As the sea advanced, so would the ‘ mari- 
time’’ climate, and so would its appropriate plants be gradually driven 
back upon their outposts, till they found a last refuge upon the 
mountain slopes and shores of western Kurope—more isolated, too, 
as being most exposed to the inroads of the sea. Of whatever date 
their origin, the species characteristic of the edge of a continent must 
naturally be sought at its circumference. Mr. Watson has allotted 
the species to their several ‘‘types”’ according to their distribution 
within Great Britain only. Still it may be said, roughly, that we 
should look among the “ Atlantic’’ (even more, the ‘‘ Hibernian’) 
rather than the ‘‘ Germanic,” to the western rather than to thé 
eastern side of Britain, for plants that may have once had their 
“metropolis” in this country. We have thought it necessary to 
give the more prominence to these considerations because it is so 
much the fashion to adopt as an axiom the necessity of a different 
epoch for every different “flora,” that few care to incur the charge 
of being unphilosophical by venturing to question the correctness of 
this view. 
But to return to the volume before us, the fourth of the ‘Cybele 
Britannica.’ Its author thus speaks of the nature of his task :— 
**So many subjects crowd upon the attention in commencing this 
fourth volume, that it becomes really difficult to answer the questions, 
as to which of those subjects are to be treated at any length, which 
of them can be slightly noticed only, and which of them must be 
passed over entirely. References to the works of other writers, where 
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