9Ji Mr. H. Seebohm on the 



They have no uncinate processes to any of their ribs. Every 

 other known living bird has uncinate processes on several 

 of its ribs*. Otherwise uncinate processes are not only 

 characteristic oi, but almost peculiar to birds^ being only 

 found elsewhere in a very few reptiles. The Screamers 

 appear to be one of the connecting-links between the Gallinse 

 and the Anseres. These two suborders are unique amongst 

 birds in the character of their pterygoids, which articulate 

 close to the palatines with very conspicuous basipterygoid 

 processes on the rostrum of the basisphenoid. They also 

 agree in having the angle of the mandible produced beyond 

 its articulation with the quadrate and much recurved. The 

 eggs of the species belonging to the two groups present 

 many points of resemblance, and in the condition of the 

 newly hatched young they agree absolutely ; but the Gallinse 

 are scbizognathous and the Anseres are desmognathous. 

 The desmognathism of the Anseres differs, however, so 

 markedly from that of the Steganopodes and Herodiones, 

 that it is easy to believe that it has been independently 

 acquired, and consequently that the points of resemblance 

 between the Gallinse and the Anseres may have been in- 

 herited from a common ancestor. 



The PalamedccC may be diagnosed by the absence of unci- 

 nate processes to the ribs. 



They further possess the following osteological characters : — 



1. They are heterocoelous in the articulation of their dorsal 

 vertebrae. 



2. They are holorhinal in the bifurcation of their nasals. 



3. They have only one xiphoid process on each side of the 

 median process of the posterior margin of the sternum. 



4. They possess basipterygoid processes which articulate 

 with the pterygoids not far from the middle of those bones. 



5. They have no lateral occipital fontanelles. 



6. The angle of the mandible is much produced and 

 recurved. 



* The gigantic, but wingless, Hesperornis regalis, tlie remains of wLich 

 are found in the cretaceous deposits of North America, had uncinate 

 processes to its ribs. 



