Ardeino- Anserine Assemblage of Birds. 99 



Herodiones. 

 The Stories and the Herons form a well-defined group of 

 birds^ possessing the following 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 have no basipterygoid processes. 



5. They have no lateral occipital fontanelles. 



6. The angle of the mandible is truncated. 



7. The palatines either almost or quite coalesce for a short 

 distance after their articulation with the pterygoids^ but when 

 they become expanded the laminae separate. 



8. The maxillo-palatines are large and spongy, and almost 

 or quite coalesce with each other and with the maxillary pro- 

 cesses of the palatines. 



The 6th character is sufficient to distinguish the Hero- 

 diones from all the other suborders, except from the Stegano- 

 podes. To complete the diagnosis, it is necessary to go outside 

 the eight characters enumerated above. The fact that the 

 tarsus happens to be shorter than the outer toe is a sufficient 

 character (though an accidental one) to distinguish the Ste- 

 ganopodes from the Herodiones. A much better character 

 is the fact that in the Steganopodes the quadrate is placed so 

 far behind the postfrontal that it causes the exoccipital to 

 extend behind the foramen magnum, giving a remarkably 

 square appearance to the back of the skull, which is also 

 observable in that of the supposed Ratite ancestor of the 

 Coiymbidse {Hesperornis) . 



The Herodiones number about 90 species, of which about 

 20 are Ciconiidfe and about 70 Ardeidee, but the two families 

 are very closely related. Nature has not drawn a very 

 definite line between them ; many of the Storks approach 

 the Herons in one or two of their characters, and many of 

 the Herons possess some Stork-like characters. The principal 

 osteological points in which the Storks ditier from the Herons 

 are as follows : — 



h2 



