REVIEWS. 253 
or six great divisions into which botanists have divided living plants, but 
these great divisions are not equally represented iu past times he 
earlier flora is chiefly acrogenous, as well represented at the coal period, 
tutes more than three-fourths of the species of existing flowering plants, 
and which acquired a predominance from the commencement of the Ter- 
tiary epoch, and may be therefore considered as characteristic of that 
eriod 
period. 
Prof. Balfour rightly remarks that the number of species has been need- 
lessly multiplied, any slight variation in form having been reckoned suffi- 
cient for specific distinction, so that a naturalist, with little knowledge of 
the present flora of the globe, ventures sometimes to decide ou an isolated 
the special parts could be mueh improved. 'Thus, at p. 38 it is stated, 
racteristie fossils, is referred to the Cretaceous period, although the 50 
strong Miocenic facies ; and more interesting still, the primordial merece 
of the flora, taken as a whole, is distinctly that of North West America. 
