Mr. R. B. Sharps' s Catalogue of Accipitres. 427 



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 i^. 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 Norwicli 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. 



