on Mr. G. R. Gray’s ‘ Genera of Birds,’ 411 
bers. Few persons would imagine, without seeing Mr. Gray’s 
book, the enormous extent to which this evil has grown, 
loading the science for ever with a mass of utterly useless 
synonyms, and compelling the unwilling naturalist too often 
to desert the works of Nature in order to disentangle the er- 
rors of man. Much of this multiplication of synonyms is, 
indeed, the unavoidable result of the number of labourers 
employed in the same branch of science, but separated by 
wide geographic intervals. The machinery for circulating 
through the civilized world the knowledge which is daily 
published in detached regions is so imperfect, that it is next 
to impossible for any individual to gain access to all the works 
which relate to his particular study. Mr. Gray’s office in the 
_ British Museum has given him great advantages in this re- 
spect, and he has availed himself of them to good purpose. 
His work appears to me highly creditable to him as a first 
attempt at bringing into order the heterogeneous materials 
which lay before him. His book is, indeed, by no means free 
from defects and inaccuracies, but they are few in compari- 
son with the errors which he has detected in the writings of 
others. It would not have been possible for any man living 
to render such a work accurate at first. One person will al- 
ways discover mistakes where another does not, and the 
greater the number of critics the more accurate the book may 
ultimately become. Having myself been engaged for a con- 
siderable time in preparing a work on the synonyms, specific 
as well as generic of the class Aves, I have been enabled by 
comparing Mr. Gray’s work with my own MSS. to judge of 
his general accuracy. In most-cases his results have entirely 
agreed with my own, and where they differed I have been led 
by further investigation to detect errors, sometimes in my 
work, and sometimes in his. It appeared desirable to em- 
body these corrections in a detailed commentary on Mr. 
Gray’s book, both for the information of those who possess 
it, and also to aid Mr. Gray in case he should publish a second 
edition. A corrected edition of the ‘Genera of Birds,’ if widely 
circulated on the Continent as well as at home, would be 
the most effectual means of introducing an uniform nomen- 
clature into ornithology, of stopping the present wanton and 
lawless multiplication of synonyms, and of opening the eyes 
of naturalists to the amount of labour which has already been 
effected in the same department by others. 
The remarks contained in Mr. Gray’s preface are very ju- 
dicious, and deserve to be read and acted upon by all zoolo- 
gical authors. In selecting and forming a permanent nomen- 
clature out of a heap of synonymous terms, Mr. Gray adopts 
