32 CLASSIFICATION OF BIRDS. 
Suborder 23. PALAMEDE.¥. 
The Screamers are supposed to be absolutely unique amongst existing birds in having lost 
the uncinate processes of their ribs. 
They may otherwise be diagnosed in various ways :— 
A. Plumage of upper parts with no spinal bare tract. B. Palate desmoguathous. 
C. Young born covered with down and able to run in a few hours. 
To this diagnosis many other characters may be added :— 
D. Number of ceryical vertebra more than 18. 





























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In haying no uncinate processes to the ribs the Palamedez are in advance of all other 
birds. The toothed birds of North America (Hesperornis and Ichthyornis) had uncinate 
processes to their ribs, and it is not unreasonable to assume that all birds once possessed 
them, and consequently that the Palamedew have lost them. Uncinate processes are charac- 
teristic of modern Crocodilia, and there can be little doubt that Crocodiles and Birds inherited 
them from common ancestors. In their pterylosis, which is characterized by the almost 
entire absence of bare tracts, the Palamedew are as archaic as the Ratite. 
~s 
