1902.] OSTEOLOGY OP THE FALCONIFORMES. 315 



My study of this group has convinced me of the soundness of 

 Dr. Suschkin's conclusions, as published in the papers to which I 

 have just referred. But whilst his investigations have extended 

 over a period of about five years, mine have been limited to a few 

 months. For this reason I withhold for the present the keys to 

 the genera, such as have been included in my former papers. 

 I hope to complete these at a later date. 



Before the publication of Dr. Suschkin's papers I had alread)^ 

 arrived at the same conclusions as are therein expressed with 

 regard to the position of the Falcones and Polybori, and of 

 Gypaetus and GypoMerax. With regard to Pandion, though I 

 felt certain it had nothing to do witli the Striges, I had not yet 

 discovered any further chie as to its real affinities. 



What follows is practically an embodiment of Dr. Suschkin's 

 views in tofo : where I have had to interpret him, that is to say 

 where I have endeavoured to express what I believe to have been 

 his views, I hope I have done him justice. 



The sub-order, then, of the Accipitres is divided into two Families, 

 the Falconidpe and the Buteonidfe. 



The family Falconidas is to be divided into two sub-families : 

 (1) the Falconince, (2) the Polyhorince. 



The former includes the genera Hmya, Herpetotheres, Micrastur, 

 Microhierax, Foliohierax, Tinnunculus, RypotriorcMs^ Hierofalco, 

 and Falco. 



The sub-family Polyborinae embraces the genera Milvago, Senex, 

 Phalcohcemts, and Polyhorus. 



The family Buteonidfe is divided into some eleven or twelve 

 sub-families, though on this point I am not quite clear, as 

 Suschkin has not definitely expressed himself on this point. But 

 he would apparently i-ecognize the following : Elanince, Pei^nince, 

 Milvince, AquiUnce, Thrasaetince, VuUicrince,Circaetin(B, Polyborince, 

 Circince, Uruhitingince, Buteonince, and Accipitrince. 



In the Elaninte are included PJlanus and Machcerhmnphus. 

 In the Perninas, Pe7'nis, Baza, Elanoides, Leptodon, and Pandion. 

 But from views he expressed in conversation, he woidd, I suspect, 

 probably make a separate sub-family for Pft?K^io?i— Pandioninfe ; 

 and most, I think, will feel this advisable. 



The Milvince include Milvus, Haliasticr, and Haliaetus, with, 

 apparently, Ictinia, Postrhmnus, and Polioaetus. Haliaetus, there 

 can be little doubt, has nothing to do with the Eagles. Polioaetus 

 Suschkin shows to be undeniably distinct fi'om Pandion. The 

 plantar tendons, as he proved, by a dissection made in this Museum, 

 are of the Accipitrine type : the skeleton in no way resembles 

 that of Pandion ; on the contrary, the pelvis and breast-bone, so 

 characteristic in Pandion, bear a quite extraordinary resemblance 

 to those of JIaliaetus. The outer toe is not more reversible than 

 in ordinary Accipitres. Haliaetus, Thalassaet^is, and Polioaetus 

 might well be made to form a separate sub- family, Haliaetince. 



The sub-family Aquilinaj includes Aquila, Uroaehts, Spizaetus, 

 JVisaetus, and Lophoaetus. The Thrasaetin?e contain Morphnus 

 and Thrasaetus, 



