ON THE ANATOMY OF CHAUNA DERBIANA. 319 
In the Gannet and the Pelican the skin is likewise emphyse- 
matous, but not exactly in the same way. In them the superficial 
surface of the cutis forms a plane surface, and the deep layer another, 
with the air-cells intervening between them, and the feather-quills 
traversing them. In Chauna, however, these two cutaneous layers are 
not definable, the whole presenting the appearance as if a non-emphy- 
sematous skin had been forcibly blown up, so as to cause its surface 
to be irregular and bubbled, more like an artificially distended mam- 
malian lung than anything else. The feathers and the semiplumes do 
not perforate the air-cells, but cause the skin to be indented where 
they are situated. 
The disproportionately massive appearance of the legs is also Page 190. 
caused by the presence of air beneath the tessellated skin, which 
extends almost to the ungual phalanges of the toes. 
The contour-feathers, many of them, possess a very feeble after- 
shaft, especially in the region of the nape, as found by Nitzsch in 
C. chavaria; and there is also a slight groove along the posterior sur- 
face of the rhachis of each. 
The rectrices are twelve in number. 
There are twenty-six remiges in one of my specimens; Nitzsch 
and Sundevall find twenty-seven. Of these ten are primaries, the 
fourth being the largest. Of the sixteen secondaries the distal 
twelve are subequal, whilst the proximal four decrease in size as they 
approach the elbow. 
The tufted oil-gland is not strikingly large; it is somewhat flat, 
with a single orifice on each side, surrounded by a circle of half-inch 
feathers which constitute the tuft. 
The tibio-tarsus is nude for its distal third, being there covered, 
as over the tarso-metatarse and digits, with small red polygonal 
scales. 
The plumage is uninterrupted, there being no spaces without 
contour-feathers, except the axillary cavities mentioned by Nitzsch, 
in which down-feathers only are to be found. The down-feathers 
are universally distributed. The nude neck-ring of C. chavaria is 
absent in C. derbiana. The feathers of the humeral tracts are con- 
siderably the strongest of the contour-feathers. 
Looked at in its entirety, the pterylosis of the Screamers is unique, 
and in no way approaches that of the Anserine birds. 
Alimentary Canal.—The palate is elongate and triangular, with 
three longitudinal rows of papilla, which are conical, large, and 
therefore comparatively few in front, smaller and more numerous 
behind. They all tend somewhat backwards. 
The tongue is just over an inch long, and # of an inch broad, 
its sides being parallel for nearly their whole length. The tip is 
