80 
assigned his plant a specific character, which is as applicable 
to other species, and he illustrated his meaning by quoting a 
synonym of Gronovius, which instead of being a Crategus is 
Amelanchier Canadensis. Succeeding Botanists could not 
therefore tell what he meant, and the second name they gave 
to the plant of Linnzus ought we think to have been retained. 
There is a large, and often, we doubt not, a very 
proper reduction of species, which in many cases have 
been created upon garden seedlings, whose peculiar features 
have been owing to domestication. ‘Too much care however 
cannot be exercised in this respect, or a greater evil will 
result from confounding different species under one common 
name, than from separating mere varieties as distinct species. 
In the genus Calycanthus for example, C. levigatus is com- 
bined with C. floridus and C. glaucus. But unless there is 
some positive evidence that the first of these plants is the 
same as the other two its great dissimilarity of appearance 
would make it desirable to keep it distinct. Again, in join- 
ing CEnothera serotina with QE. fruticosa, two more widely 
different plants are united, than OZ. glauca and fruticosa 
which are separated. 
We might make some similar observations upon genera, 
such as the union of Geum with Sieversia, Bartonia with 
Mentzelia, and of OZnothera with Godetia, while Horkelia is 
separated from Potentilla, Vachellia from Acacia, and Cerasus 
from Prunus; but these are matters of less importance. 
In conclusion it is only necessary to call attention to the 
supplementary matter appended to the volume. It shows 
the result of Dr. Gray’s examination of European herbaria, 
so far as the earlier orders are concerned, an advantage he 
had not enjoyed when the first and second parts of the work 
went to press. Nothing can indicate more clearly than this 
supplement the unwearied diligence with which Dr. Gray 
studied the important materials then for the first time placed 
before him. 
The authors may be congratulated upon having proceeded 
so far in their publication, which, it is not too much to say, 
is one of the most important additions to systematical botany 
that has appeared for many years. 
