Vlll 
PREFACE. 
Work, I should probably at the present moment be inclined to reduce still further the genera of a few 
of the subfamilies. It must also be remembered that I have endeavoured to adopt such names oidy 
as maybe supposed to designate genera; those of the lower divisions or subgenera are given under 
the names of the species which form their type ; and I have added the synonymous names of the genera 
as well as those of the subgenera, in the form of notes to the generic name employed. 
The difficulties in the way of defining the value of a division are indeed very great, and its adoption 
must always depend much on individual opinion, as well as on the extent of our knowledge of species ; 
for an isolated species often appears to form the basis of a good division when examined by itself, while 
the distinction vanishes at once when the bird is examined in connection with the entire mass of species 
forming the group to which it belongs. Genera, too, are not unfrequently established on unique 
specimens which are difficult of access, and have been recorded without the aid of figures to give an 
accurate idea of their forms ; but of such I may state that there are only a very few instances in which 
I have not had the good fortune to obtain the means of examining either the specimens themselves or 
drawings made from them. Great caution is also required in dealing Avith genera established, as some 
have been, on falsified or distorted specimens, such, for instance, as Erolia , Barb ilan ius = Spar a ctes, 
fly reus, Autrochenon , and Anarhynchus ; to which I may add Verrulia , which I have recently learned 
is considered to have been established on a pigeon furnished Avith wax Avattles and a false tail, for Avhich 
reason it becomes necessary to blot out this genus from among the Gourince. 
Great obstacles frequently occur in the Avay of ascertaining the true and proper (that is to say, the 
earliest-employed) generic names, many having been first published in Transactions, Journals, Books 
of Travels, and even more miscellaneous works, Avhich have not been much examined for this purpose 
until of late. I may mention tAvo examples illustrative of this difficulty, which require correction in 
the present Work. I had been led to suppose that Phaleris of M. Temminck (1820) Avas the oldest 
name for the division to Avhich I have applied it in the body of the Work ; but I have lately found that 
that division was proposed in the previous year (1819) by Merrem in “ Ersch und Grub. Encycl.” under 
the name of Simorliynchus : and I have been informed by Dr. Hartlaub ( AAdio Avas indebted for the 
information to the Prince of Wurtemburg) that the division for which I have adopted Mr. SAvainson’s 
name of Calurus (1837) was proposed as far back as 1801 by Pedro de la Llave, in a Mexican 
publication entitled “ Registro trimestre,” under the name of Pharomachrus. 
Such changes Avith regard to generic names must continually take place until our knoAvledge of all 
that has been done by previous Avriters becomes registered in a general Avork, by means of which 
the information thus eventually obtained by dint of continued application cannot fail to become the 
foundation of that most desirable object, a uniform system of nomenclature. 
The Index of Generic Names referred to in this Work will be found to extend to upwards of 2400 ; a 
greater number than has been recorded in any previous publication. Of the genera adopted (amounting 
