332 DR. GADOW ON THE ANATOMY OF PTEROCLES. [Mar. 21, 



large group and the Fowls the other, because then this Plover- 

 Pigeon group would include a form, viz. Pterocles, which we know 

 to be more closely allied to the Rasores than to Charadrius. It 

 must also be remembered that Snipes and Gulls are closely related 

 to the Plovers ; and of course Pterocles cannot be placed in such a 

 position as would indicate that it is more closely related to the 

 Gulls than to the Grouse. Thus it will be best to make a group or 

 family Pterocletes, as Mr. Sclater has done, coordinate with those of 

 Pigeons, Plovers, Gull, Fowls, and the like. 



On the other hand, if we are to answer the straightforward question 

 Is Pterocles more nearly allied through its ancestors to the Pigeons 

 or to the Fowls? we are compelled to say that they are nearest to the 

 Pigeons. Of course they have many features in common with the 

 Fowls ; but in no case we can include them under the latter, for the 

 following reasons : — 



Pterocles shows some, although only a ievj, anatomical points 

 which we only find amongst the Columbidse, whilst all the other 

 numerous points in which it resembles the Fowls are such as must 

 have been common to the old ancestral Stork, as we find them again 

 in some of the Limicolae. But some of its Columbine features it is 

 impossible to trace so far back, as they indicate a very high degree 

 of specialization. Pterocles must have branched off from those 

 birds which we may term " incipient Pigeons," and then, for reasons 

 we can only suggest (perhaps similar conditions of life, and the like), 

 have preserved and developed many of those old characters which 

 the Fowls have also inherited from the same source, and have them 

 developed in a similar way, as living under the same conditions. 



The main part of the ancestral or incipient Pigeons at the same 

 time started in another direction, losing, as they proceeded, many 

 of the old characters ', and acquiring numerous new ones, till they 

 became that highly specialized group which is now called Columbse. 



* Among the most important characters common to the ancestral stock 

 whicli the Pigeons have lost, or are in process of losing, are the fullowing : — 



1. The Pigeons have nearly completely lost the ciecal appendages of the 

 rectmn. 



2. There seems to be a tendency to lose the ambiens muscle, as in many of 

 the Pigeoue it is completely absent, and in others this muscle is unstable in its 

 presence. 



3. They have lost the aftershaft to the feathers. 



4. They have almost completely lost their nestling plumage, and the old 

 character of being autophagous birds, as' their young are now hatched nearly 

 nude, blind, utterly helpless, and depending entirely on their parents, and have 

 to spend a considerable part of their childhood in a very imperfect state. 



