EXPLANATORY NOTE. 
the claw ; 7; the length of the claw of that toe. Thus, with 
reference to the Golden Eagle, p. 40 — 
Male, length 33, extent of wings 72, wing from flexure 24, 
bill along the ridge 2 T %, tarsus 4, middle toe 2-f^ its claw 1 T ^. 
Of the female there are given only the length from the tip 
of the bill to that of the tail, and the extent of the wings. 
In the next paragraph are stated some of the more remark- 
able habits of the species, its distribution, a short description 
of its nest and eggs* and some other circumstances. 
Then follow the vernacular names by which it is known. 
And, lastly, reference is made to a few works in which 
the species is described, namely, the Sy sterna Naturae of Lin- 
naeus, the Manuel d’Ornithologie of M. Temininck, and the 
British Birds of Mr MacGillivray. On referring to these 
works, the student will find references to others. 
A few words now as to Names. The Latin word Avis, 
which corresponds with the English word Bird, being femi- 
nine, the Ordinal names employed ought in strictness to be 
of the same gender. Accordingly, instead of naming the Ra- 
pacious Birds Raptores, as is usual, I call them Raptrices. 
The names of the Families being always adjective, must ne- 
cessarily agree in gender with the substantive Avis, to which 
they refer: thus, Vulturine, Falconing, Corvine, Co- 
lumbine. The generic names ought always to be of Greek 
or Latin origin. Names formed by giving a Latin termina- 
tion to a modern word seem ludicrous, and therefore I have 
not in any case used them, although in a few instances I have 
adopted from authors such vernacular names as Sula and 
Gavia, which harmonize in sound with Latin words. Spe- 
cific names are either adjective, as regalis , prate7isis, pileatus , 
coeruleus, and agree in gender with the generic name to which 
they refer ; or substantive, in which case they need not agree 
in gender, as Corvus Monedula , JErithacus Rubecula. When 
a species is named after a naturalist, it seems best to give 
the name unaltered, further than by Latinizing its terminal 
syllable : Motacilla Yarrell-i , Motacilla Brisson-i , Sterna Mac - 
dougall-i. 
