1882.] DR. GADOW ON THE ANATOMY OF PTEROCLES. 331 



4. The most specialized of the Rasores (that is to say, the typical 

 Alectoromorphfe) we have to put at the eud of the right branch. 

 The Tetraonidse and the Cracidfe are those which, of all the Rasores, 

 show the greatest resemblance to other families ; they must there- 

 foi'e form the earliest or lowest twigs of the Rasorial branch ; con- 

 sequently we have to put their special roots nearest to the biggest 

 and at the same time more indifferent stock. 



But now as to Pterocles. 



1. No doubt the Sand-Grouse are more nearly allied to the Rasores 

 than the Pigeons are. Consequently we must seek for their root 

 between the Rasorial and the Columbine branch. 



2. Again, the Sand-Grouse are more nearly allied to the Pigeons 

 than to the Plovers ; thus their branch must be put nearer to the 

 Columbine branch than to that of the Plovers. 



Fig. 8. 



Diagram showing the supposed relationship of the Pteroelidse. 



This conclusion and the former can be reconciled only if we put 

 the Sand-Grouse branch at x ; and as this places them pretty nearly 

 in the centre of our hypothetical table, it proves that our final 

 conclusion cannot be far from right. 



The fact is that birds just a little less specialized than Pterocles 

 — in other words the direct ancestors of Pterocles — would contain 

 all that is necessary to develop them into either Fowls, Pigeons, or 

 Plovers. 



Considering these circumstances, we see once more that, as Mac- 

 gillivray and Professors Sundevall and Garrod have maintained, the 

 Pigeons are not so closely related to the Fowls as is generally sup- 

 posed. 



It would be extremely difficult to arrange the birds represented in 

 our table into families and groups as is required iu a practical system. 

 If we want to divide them into only three groups — Plovers, Pit^eons 

 and Fowls — of course Pterocles lias to go with the Pigeons ; but this 

 would not express its close relationship to the Tetraonidse. A^ain 

 we cannot include the Pigeons and Fowls under one large group' 

 and the Plovers under a second, because the Pigeons must be placed' 

 along with the latter. And Pigeons and Plovers cannot form one 



