1882. | DR. GADOW ON THE ANATOMY OF PTEROCLES. 331 
4. The most specialized of the Rasores (that is to say, the typical 
Alectoromorphz) we have to put at the end of the right branch. 
The Tetraonidze and the Cracide are those which, of all the Rasores, 
show the greatest resemblance to other families; they must there- 
fore 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. 
Diagram showing the supposed relationship of the Pteroclide. 
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 
tia 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 in a practical system. 
If we want to divide them into only three groups—Plovers, Pigeons 
and Fowls—of course Péerocles has to go with the Pigeons ; but this 
would not express its close relationship to the Tetraonide. Again 
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 
