427 
Mr. R. B. Sharpe’s Catalogue of Accipitres. 
parts become at length pure white; such pure white birds 
are much rarer than the variegated ones, and are, from their 
greater shyness, less easily shot. I obtained two specimens 
of a darker variety, in which the white on the back and under¬ 
parts is replaced by a dirty yellow-brown, which is lighter on 
the throat and belly than on the breast and back; these spe¬ 
cimens, however, may be recognized as belonging to F. niveus 
by the very distinct transverse bars on their wings and tail. 
On a minute anatomical comparison of F. limnaetus and F. 
niveus some differences in the structure of the skeleton may 
be observed, which, however insignificant, enable me to dis¬ 
tinguish between the skeletons in my possession. Thus, for 
example, the space between the processus maxillares of the 
two bones of the palate is less in F. limnaetus than in F. 
niveus , and in consequence the mussel-shaped apophysis 
of the palate of the upper mandible-bone contribute more to 
the formation of the hard palate in the latter than in the 
former; also in the skull of F. limnaetus , where the outer 
edge of the palate-bone passes over to the ossa omoidea, 
there is on each side a sharp angle or corner, directed out¬ 
ward and backward, whilst in F. niveus the outer edge bends 
gradually into the backward one. All these differences, as 
well as the general anatomy of these birds, I have described 
more minutely in a separate article in the sixth volume of the 
Treatises of the Society of Natural Philosophy of Batavia.” 
Mr. Sharpe gives the description of a Sumatran nestling 
of the paler race in the British Museum, which seems not to 
differ materially from the Java specimens described by Dr. 
Bernstein. 
Whether the two races are really specifically distinct, or 
only different in the darker being an hereditary melanism of 
the paler, and whether the pale birds ever assume a plumage 
resembling those which are melanistic ab ovo *, must, I think, 
remain an open question. Should the two races be admitted 
* A fuliginous specimen from Java in the Norwich Museum has some 
yellowish white feathers scattered about the lower portion of the tarsi, 
and some wholly fuliginous specimens certainly show more variation of 
tint than others. 
