Page 189. 
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818 ON THE ANATOMY OF CHAUNA DERBIANA. 
52. ON THE ANATOMY OF CHAUNA DERBIANA, 
AND ON THE SYSTEMATIC POSITION OF THE 
SCREAMERS (PALAMEDEID4).* 
(Plates XIV—XVII). 
In his memoir “on the systematic position of the Crested Screamer 
(Palamedea chavaria),” published in the “ Proceedings” of this 
Society,t Prof. Parker has placed that bird among the Anseres, and 
away from the Rallide, with which it had been generally associated. 
In his “ Classification of Birds,’’t Prof. Huxley adopts the same view 
as Prof. Parker. Both these distinguished authorities base their 
opinions on anatomical considerations; it therefore behoves me to 
attempt to substantiate the different views expressed by me in my 
paper “on certain muscles of Birds, and their value in Classifica- 
tion,”§ as it is so considerably at variance with that of the authorities 
just mentioned. 
The great extent to which the skeleton is permeated with air ren- 
ders the features presented by the different bones of Chauna less 
distinctive than in the majority of birds. For this reason the soft 
parts will be first considered. 
Cutaneous System. Pterylosis.—Nitzsch has described the ptery- 
losis of Palamedea cornuta and Chawna chavaria; and, as might be 
expected, O. derbiana does not differ in any important particulars from 
the latter. As he remarks, the most striking point observed in the 
plucked bird is the extreme whiteness of the surface, which depends 
on the fact that the skin is almost universally emphysematous to the 
depth of nearly a quarter of an inch. On préssing with the finger, 
the characteristic crackling of a tissue filled with air is most marked, 
the only places in which it is absent, or nearly so, being the anterior 
surfaces of the upper ends of the tibia, and, to a less degree, two 
triangular spaces, equilateral, with their bases towards the middle 
line, situated one on each side over that part of each pectoral region 
which is near the head of the humerus, in the apex of the larger 
triangular surface bounded by the superior and axillary margins of 
the great pectoral muscle. 
* “Proceedings of the Zoological Society,” 1876, pp. 189-200. Plates XII— 
XV. Read, Feb. 1, 1876. 
+ “Proceedings of the Zoological Society,” 1863, p. 511. 
t “ Proceedings of the Zoological Society,” 1867, p. 415. 
§ “ Proceedings of the Zoological Society,” 1874, p.111. (Supra, p. 208.) 
