HO 



NEW YORK STATE MUSEUM 



the vertical portion of a niaxillopalatine is entirely different from 

 any true falcon that the writer has ever had the opportunity to 

 examine. This latter is very large, purely osseospongeous in tex- 

 ture, lofty, bulbous, and nearly fills the rhinal chamber. Anterior 

 to it the nasal septum is quite complete. 



Polyborus having a much more elongated skull than we find in 

 the average Falco, we naturally meet in it a more acutely V-shaped 

 mandible, but in other respects it possesses many of the falconine 

 characters. One point always distinguishes it, however, for the 

 ramal vacuity in the lower jaw of the caracara is invariably present, 

 being elongoelliptical in outline, large, and with a small circular 

 foramen just posterior to it. Either articular cup shows behind a 

 vertical, bony ridge or crest, and, agreeing with the major portion 

 of the skull proper, this jaw is largely pneumatic. 



Fashioned practically upon the same plan as in the genus Falco, 

 the hyoideau arches of Polyborus 1 u t o s u s exhibit but one 

 striking difference, for in it we are struck with the unusual length of 

 the ccratohyals, and these latter may meet mesially at their anterior 

 ends. In the trachea the ossified trachial rings are not as narrow as 

 they are seen to be in the falcons. A good, strong and ossified 

 pcssulus develops in the inferior larynx. 



Some interesting points are to be seen in the rest of the trunk 

 skeleton of this caracara. In its shoulder girdle it essentially agrees 

 with Falco mexicanus, differing only in having a rudi- 

 mentary hypocleidium on the os furcula, and the coracoids are 

 stouter bones, and the foramen that perforates the shaft of either 

 one of them is well within the border. There is the same evident 

 tendency for the scapular process to curve round to meet the head 

 of the bone. The coracoids in this vulturine falcon also profoundly 

 cross each other in the coracoidal grooves of the sternum, the right 

 one being in front. 



FlC. 5 \ Pelvis of Polyborus cheriway, seen upon right lateral view. 

 Natural size 



