128 NEW YORK STATE MUSEUM 



palatines may be narrow (Ictinia) or markedly broad transversely 

 (Elanus). Mandible without ramal vacuity, and fairly strong 

 (Ictinia) or notably weak (Elanus). 



Os furcula may have its hypocleidium rudimentary (Ictinia) or 

 absent (Elanus). 



The scapular process of a coracoid does not reach the clavicle. 

 (The union of the clavicles inferiorly is weaker in the Milvinae than 

 any others of the suborder.) 



In the sternum the manubrium is always very small ; the keel may 

 extend the entire length of the sternal body (Elanoides, Ictinia) or 

 it may not (Elanus) ; the xiphosternum may be deeply notched 

 (Ictinia), or fenestrated once on either side of keel (Elanus), or it 

 may show a shallow emargination on either side only (Elanoides). 

 Ribs and vertebrae liable to vary. Postpubic element of pelvis 

 always interrupted. Ilia not in contact anteriorly, and the postaceta- 

 bular part of the bone not especially bent downward and forward. 



Fibula may be very long (Ictinia) or even complete (Elanoides). 

 Form of tarsometatarsus varies ; it may have the hypotarsus repre- 

 sented by two small processes (Ictinia), or be in one subcubical 

 piece with a single vertical perforation for the tendons (Elanoides). 

 Tubercle for the insertion of the tendon of tibialis anticus muscle 

 occupies the middle of the shaft. Digits of pes differ remarkably; 

 in all, the three first joints of fourth toe subequally abbreviated, the 

 distal one of the three may be quite rudimentary (Elanus) ; the 

 prebasal joint of third toe more or less shortened; the basal joint of 

 second toe always much abbreviated, and in Ictinia it permanently 

 fuses with the joint next beyond it. 1 



Falconoidea 



Falconidae. Raptorial birds, which in addition to the subordinal 

 characters exhibit the following: a septum narium always ossifies 

 to a greater or less extent; the supraorbital portion of a lacrymal 

 conspicuously produced outward and backward. A long, more or 

 less platelike, vomer present. 



Sternum with its manubrium developed; and its coracoidal 

 grooves usually decussate to a greater or less degree. 



1 This remarkable condition occurs in both feet of the specimen at my hand, and 

 has all the appearance of being the usual one in this species. Haliaetus leuco- 

 ce-phalus may exhibit the same character. I would add here that there is no 

 likelihood of mistaking the skeletons of any of our kites (Elanoides, Ictinia or Elanus) 

 for the skeleton of any other form of the suborder. They, however, are wonderfully 

 different among themselves. Ictinia is a miniature Buteo, but it possesses the character 

 of the second toe, just mentioned and has rudimentary basipterygoid processes. 



