274 Mr. H. Seebohm’s Corrections of 
disallow the claims of many species to be considered new. 
These identifications with previously described species will 
appear in their proper places in the synonymy of the various 
birds treated of in the volume, but, from the nature of the 
work, without note or comment. Tomy mind, whatever value 
may attach to an opinion is increased at least tenfold by a 
concise statement of the grounds upon which it is based, so 
that the readers may be able to form an opinion of their own, 
instead of accepting it on the authority of even the best 
expert. Some of our most accurate writers on ornithology 
have neglected this important point, partly perhaps from a 
mistaken endeavour to be brief, and partly, it is to be feared, 
from an unwillingness to commit themselves to a definite 
line of argument, the accuracy of which might hereafter be 
impeached. Ihave frequently been told, when asking for the 
reason why an opinion in which I could not coincide was 
expressed, that the writer had no doubt that he had excellent 
reasons at the time for coming to the conclusions which he 
recorded, but that now, after the lapse of some years, he was 
not able to recall his former line of argument to memory. 
Such replies are eminently unsatisfactory. The day in which 
opinions were accepted solely on authority is past. Probably 
we are in danger of rushing to the opposite extreme, and are 
more inclined, in those cases where the evidence does not 
‘satisfy our reason, to give the casting vote in favour of 
doubt. 
It appears to me that new material is so continually coming 
forward, and old material is so frequently being raked up 
from the nooks and corners where it has been lying hid, that 
no ornithological opinion can be considered final, or even of 
much value, unless accompanied by the statement of the facts 
upon which it is based. | 
In addition to the “slaughter of the innocents,” which I 
propose to justify, to the best of my ability, im the present 
paper there are also numerous errors of identification to 
correct, which also require some explanation more full than 
-s consistent with the plan of the ‘Catalogue of Birds.’ 
Acrocephalus arabicus, Heugl. Orn, N.O.-Afr, i, p. 289 
