FTEROCLETES 317 



The deep flexor tendons fuse at the ankle, but no branch 

 is given off to the small hallux ; this digit has, however, a 

 special flexor hallucis brcvis. GADOW concludes his survey 

 of the muscles of the bird with the following remarks : ' Of 

 all the other muscles of the leg (excluding ambiens, peroneus, 

 and absent flexor hallucis slip) there is none that shows any 

 practical difference between sand grouse, pigeons, and even 

 (if we include them in our comparison) the plovers. On the 

 whole, however, the myology of Pterocles indicates that it is 

 more nearly allied to the pigeons than to any other group of 

 birds.' 



The general aspect of the skull of Pterocles arenarius is 

 much like that of a similarly sized pigeon. The nostrils, 

 however, are more distinctly holorhinal, thus leading towards 

 the gallinaceous birds. They end on a level with the ends of 

 the nasal processes of the premaxillaries, and do not narrow 

 at all at their broadly rounded terminations. As is the case 

 with Goura, Opistliocomus (a fact of possible importance), and 

 some other holorhinal birds, a plate of bone underlies the ex- 

 tremity of the nostrils, reducing the extent of the orifices. 



As in pigeons the ectethmoids are very solid plates of bone 

 which fuse with the lacrymals, and nearly reach the jugal 

 bar ; only the minutest foramen perforates this plate above. 

 Syrrhaptes l agrees so far with Pterocles, but has a rather 

 more vacuolated interorbital septum. 



The post-orbital and post-frontal processes are long, and 

 nearly (Pterocles) or quite (Syrrhaptes) fuse at their extremi- 

 ties, as in some gallinaceous birds. 



The niaxillo-palatines are not like those of pigeons ; they 

 are, as in gallinaceous birds, slender curved hooks. 



The basipterygoid processes are well developed. 



There are fifteen or sixteen cervical vertebrae. 



' In almost all those respects,' remarked HUXLEY, ' in which 

 the grouse differ from the fowls they approach the pigeons ; and 

 an absolute transition between these groups is effected by the 

 Pteroclidtp, whose popular name of " sand grouse " might fitly 



1 See PARKER, ' On the Osteology of Gallinaceous Birds,' &c., Trans. Zool. 

 Soc. vol. v. 



