84 NEW YORK STATE MUSEUM 



Ictinia has its pars plana much of the same form that we found 

 it to have in Circus, but still rather more like the corresponding 

 part in a specimen of Buteo b . calurus. In all three the 

 upper part of this osseous lamina is somewhat adpressed against 

 the adjoining mesethmoid, but not sufficiently, however, to prevent 

 the existence of the anteroposterior foramen there. Ictinia has a 

 small central deficiency in its interorbital plate, and the septum 

 narium is complete, being met above by the mesethmoid. Within 

 the orbital cavity we find the several nervous foramina in the an- 

 terior wall of the brain case, thoroughly individualized. The infra- 

 orbital bar is straight and slender, and the quadrate bone essentially 

 agrees in form with the Buteos and the harriers. 



We find a good differential character in the limits of the tem- 

 poral fossa upon the lateral aspect of the cranium. In the Missis- 

 sippi kite it is quite extensive; less so is Buteo; while in Circus 

 the area for the origin of the temporalis muscle seems to be con- 

 fined between the postfrontal process, and the enlarged upper por- 

 tion of the auricular orifice in this harrier. 



Upon the basal aspect of the skull the bony parts in Ictinia and 

 Circus are essentially the same, though a few differences do exist; 

 as for instance the foramen magnum is more circular in outline in 

 the kite than it is in the harrier; its pterygoids are comparatively 

 much stouter; the lateral angles of the basitemporal are not so 

 prominent as they are in Circus ; the posteroexternal angles of the 

 palatines are squarer in Ictinia, and although its maxillopalatines 

 are relatively not as long, they unite with greater intimacy in the 

 middle line. The vomer in Ictinia agrees fairly well with what 

 was found in Circus, but it is disposed to ossify but feebly. 

 Usually it thoroughly ossifies in the Buteos, and the various points 

 we have been comparing in the last paragraph, agree better between 

 Ictinia and Buteo than they do between Ictinia and Circus. The 

 last two genera mentioned agree in the characters of their lower 

 mandibles. Further, we find that the ossifications of the hyoidean 

 arches; the sclerotals of the eyeballs; the trachea, and probably the 

 intrinsic ossifications of the ears in Ictinia all essentially agree with 

 the corresponding structures as we found them to exist in Circus. 

 Comparatively speaking, the rhinal chambers in the Mississippi kite 

 are not as capacious as we often find them in other Falconidae ; 

 the superospongy portions of the maxillopalatines are scanty and 

 intimately united with the nasals and nasal septum. 



