Ardeino- Anserine Assemblage of Birds. 101 



they meet on one vertebra, and amongst the Ardeidie the 

 genus Nycticorax is aberrant, the two ventral processes sel- 

 dom quite meeting. Scopus is a Stork in all points except 

 the 4th ; the coracoids slightly overlap *. 



The Herodiones are distributed throughout the temperate 

 and tropical regions of both hemispheres. 



Steganopodes. 

 The Pelecans and their allies possess an external character 

 which distinguishes them from all other birds. The hallux 

 is united by a web to the inner toe, so tliat these birds are 

 completely web-footed. They possess the following osteo- 

 logical characters : — 



1. In the articulation of their dorsal vertebrse they may 

 be either heterocoelous or opisthocoelous. 



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



3. They may have either one or two lateral xiphoid pro- 

 cesses on each side of the median process of the posterior 

 margin of tlie 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 may or may not coalesce with each other 

 along the whole lengtii of their expanded parts. 



8. The maxillo-palatines are large and spongy and coalesce 

 with each other and wdth the maxillary processes of the 

 palatines. 



They may be distinguished from all the other suborders 

 by the 6th character, except from the Herodiones, which 

 have the tarsi much longer than any of the toes. 



The Steganopodes contain only half a dozen genera ; but, 

 with one exception, these differ so much from each other, 

 that each genus may fairly claim to be placed in a distinct 

 family. Witli the exception of Plot us, which appears to be 

 very nearly allied to Phalacrocorax, every genus differs in at 



* The TIammer-head further resembles tlie Storks and differs from 

 the rierous in flying with its neck stretched out, instead of being folded 

 up until the head comes between tlie shoulders. 



