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Show 1882.] DR. GADOW ON THE ANATOMY OF PTEROCLES. 331 4. The most specialized of the Rasores (that is to say, the typical Alectoromorpha?) we have to put at the end of the right branch. The Tetraonida? and the Cracida? are those which, of all the Rasores, show the greatest resemblance to other families ; they must therefore form the earliest or lowest twigs of the Rasorial branch ; consequently 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. N o 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 Pteroclidae. 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 Macgillivray and Professors Sundevall and Garrod have maintained, the Pigeons are not so closely related to the Fowls as is generally supposed. 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 Pterocles has to go with the Pigeons ; but this would not express its close relationship to the Tetraonida?. 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 Pigeous and Plovers cannot form one |
