24 THE GAME BIKDS AND WILD FOWL 



ORDER PEDIOPHILI.— THE SAND=QROUSE. 



I HAVE adopted Bonaparte's term Pediophili for the present order in 

 preference to that of Ptebocletes suggested by Dr. Sclater, not only 

 because, as Professor Newton points out, the latter is based on a grammatical 

 misconception, but because the former possesses the additional claim of priority. 



The Sand-Grouse form a remarkably isolated group of birds, showing affinities 

 (especially in the digestive organs) with the Game Birds, and (in their osteological 

 characteristics) with the Pigeons; being, as was pointed out by Huxley thirty 

 years ago, so completely intermediate between these groups that they cannot be 

 included within either of them without destroying its definition, although perfectly 

 definable themselves. Some systematists, as for instance Sclater and Stejneger, 

 elevate them to the rank of a separate order ; and all things considered this seems 

 to be the wisest course: others, as Eeichenow and Piirbringer, regard their 

 characters of only sufficient importance to rank as a sub-order. Some naturalists 

 include them in the great natural order of the Columbifobmes ; others, with 

 equal authority, include them in the equally distinctive group of Gallifobmes. 

 The Sand-Grouse are one of the few ancient surviving links in the now broken 

 chain of avine descent; and it seems impossible, in the present state of our 

 knowledge, to say to which existing group of birds they are most closely allied. 

 Their double-spotted egg (having underlying as well as surface markings) and 

 precocious nestling, gives the casting vote in favour of placing them in closest 

 proximity to the Gallifobmes, although on the other hand their pterylosis is 

 similar to that of the Columbifobmes. 



In the Sand-Grouse the sternum contains two notches on each side of the 

 posterior margin, the inner one in some instances being reduced to an aperture or 

 foramen. In the modification of their cranial bones the Sand-Grouse are 

 schizognathous, whilst their nostrils are schizorhinal ; although this latter is a 

 variable character and thus apparently of comparatively^small taxonomic value. 

 Amongst their external characters may be mentioned the following: oil-gland 

 nude; hallux, small, rudimentary, and sometimes absent; body feathers with 

 well-marked after-shafts; fifth secondary absent. So far as is known the Sand- 

 Grouse moult only in autumn ; the young are hatched covered with down, and 

 able to run almost as soon as they break from the shell. 



Sixteen species of Sand-Grouse are at present known to science, and these are 

 all contained in a single family. These birds are all confined to the Old "World. 



