360 FLAMINGOES, DUCKS, AND SCREAMERS. 
as deep as a cormorant, while when pursued nothing more than the head and neck 
appears. On the larger Indian rivers, writes Mr. Hume, “they will float down 
with the stream for a couple of miles, and if not hungry, they rise and fly back 
again; but more commonly they fish their way back, diving incessantly the whole 
way, and, despite their activity, taking a long time to make their way back from 
where they started from. When gorged, they often sit on some rock in the middle of 
the water, sitting very upright and cormorant-like, often half opening their wings to 
the sun. In the interior, where you find them in smaller streams, they are rarely 
in parties of more than three or four—most generally at that time in pairs 
then they are either flying up-stream or floating down, twisting round and round 
in the rapids, or fishing vigorously in some deep pool near the foot of a waterfall 
or rapid.” Although generally silent, mergansers utter at times, especially when 
on the wing, a harsh, unmusical kurr. Three beautifully coloured birds from the 
mountains of Chili, Peru, and Ecuador, constitute the allied genus Merganetta. 
and 

THE SCREAMERS. 
Order PALAMEDEXZ. Family PALAMEDEIDZ. 
If we examine the skeleton of any ordinary bird, such as the one represented 
on p. 292 of the preceding volume, it will be noticed that some of the anterior ribs 
are provided with backwardly-directed projections, known as uncinate processes. 
If, however, we observe that of one of the peculiar South American birds designated 
screamers, we shall not fail to be struck with the absence of these processes, and as 
they are present in all other birds and many reptiles, it will be evident that the 
screamers are a very specialised group, although in some other ways they are 
generalised. Although these strange birds exhibit certain resemblances in their 
internal anatomy to the storks and cranes, it is now generally considered that their 
nearest affinities are with the ducks and flamingoes. Agreeing with those two 
groups in the features mentioned at the commencement of the chapter, the screamers 
are readily distinguished from both by their short hen-like beaks, and medium- 
sized legs, of which the toes are not completely webbed, but furnished with long 
claws, the claw of the first toe being specially elongated. Internally, in addition to 
the absence of uncinate processes, they are characterised by the presence of distinct 
basipterygoid processes on the rostrum of the skull, by the number of vertebree in 
the neck being more than eighteen (which is not the case in the two allied orders), 
and likewise by the absence of any bare spinal tract in the plumage of the upper- 
parts; while the angle of the lower jaw, although recurved, is not much produced 
backwards. Another peculiarity is to be found in the circumstance that the skin 
when touched is yielding and crackling, owing to the presence of a layer of air- 
cells, which communicates to it a bubbly appearance. In colour and texture their 
egos resemble those of the geese. 
The screamers are birds of the size of a swan, but of totally different appear- 
ance, having a hen-like beak, with a waxy growth at the base, medium-sized neck, 
very inflated crop, a pair of powerful spurs on the front of each wing, and the long- 
toed legs bare to a considerable distance above the ankle-joint. Although the 
