278 MR. W. p. PYCRAFT ON THE [-^P^'- 1^> 



common with certain of the Gruos on the one hand, and of the 

 Steganopodes and Herodiones on the other. 



It will be the aim of the present paper to supplement the 

 evidence of these affinities which has been so far collected, by a 

 careful study of the Osteology of the Falconiformes,- — a study 

 which shall embrace comparisons of the skeletons of the forms 

 not now regarded as allies of this group. By these means it may 

 be possible to arrive at more definite conclusions concerning the 

 probable inter-relationship of the undoubtedly allied forms, and of 

 their phylogeny. 



ii. The Skull of the Adult. 



It seems to be impossible to draw up, in concise terms, any 

 definition which shall serve us to readily distinguish the skull of 

 the Falconiformes from any skull of what we are agreed to regard 

 as the near allies of this group. This is due partly to the fact 

 that the group contains some very aberrant forms with peculiar 

 skulls, and partly to the fact that the characters upon which 

 we are wont to rely for taxonomic purposes present us with many 

 grades of perfection even amongst the smaller divisions of the 

 group. Thus, the palate afibrds a series of gradations between 

 complete desmognathism and complete schizognathism ; basi- 

 pterygoid processes may be very well developed or completely 

 absent ; the lachrymal may be free or fixed ; the nares may be 

 pervious or impervious ; and so on. 



The best that we can do is to say that no indirectly desmo- 

 gnathous Falconiform skull owes this form of desmognathism to 

 the intervention of the vomer alone — as in the Oariamidse. Again, 

 no indirectly desmognathous Falconiform skull combines this form 

 of desmognathism with a large vomer and a large anterior palatal 

 vacuity. No Falconiform skull has supra-orbital grooves, or has 

 the palatines fused in the middle line posterioi-ly. Finally, all 

 the skulls of this Order have an ossified orbito-sphenoid. 



The resemblances which the skull of the Falconiformes presents-, 

 through cei'tain of its members, to the Steganopodes, Grues, and 

 Striges will be pointed out and discussed in the following 

 remarks. 



The Occipital Region. 



The plane of the occipital f oilmen varies, from an oblique angle 

 to one almost pai-allel with the long axis of the skull. The forms 

 in which the plane is almost horizontal are those which represent 

 the higher types — the Eagles, Buzzards, and Falcons, The foramen 

 in these forms thus looks downwards, instead of downwards and 

 backwards. 



In the Falcons, Buzzards, and Cathartfe there is a prominent 

 cerebellar dome. This is less well-marked in the Vultures and 

 Eagles, and in Serpentarius. 



The supra-foraminal ridge is fairly well-marked in every 



