OSTEOLOGY OF BIRDS IO9 



forward directed spine occurring both above and below the head of 

 the quadrate. This latter bone is still further held in place by two 

 other osseous spurs, one above and one below at its posterior aspect 

 within the concavity of the bony ear. A quadrate is large but 

 presents nothing peculiar ; it simulates the bone in the falcons. The 

 zygoma is moderately slender, straight and nearly of uniform 

 caliber. Rather a large deficiency exists in the interorbital septum, 

 and it may merge, and I believe it usually does, with the foramen 

 rotundum, and the otherwise distinct foramen above it for the first 

 pair. These last mentioned nerves traverse a double, open groove 

 on their way to the rhinal chamber, and enter through a foraminal 

 aperture there that is but partially separated off from the larger ex- 

 ternal one over the main part of the pars plana. This latter is 

 large and thickish, being subquadrilateral in outline. 



A lacrymal is but -semifalconine in its morphology, the supra- 

 orbital portion being somewhat short, carried out to a point, and 

 presenting much of its surface to the outer aspect. The constriction 

 made by the lacrymal duct is definite, and the descending part of the 

 bone is narrow and long, reaching to the zygomatic bar. Internally 

 it hardly touches the pars plana, and never fuses with any of the 

 bones it articulates with, as the nasal and frontal. On the basal 

 aspect of the skull we find a pterygoid, short, straight, very slightly 

 twisted upon itself, with its anterior margin sharpened. The 

 Eustachian tubes are thoroughly closed in, open by a common en- 

 trance anteriorly, over an underlying pointed shield of bone. The 

 rostrum of the basisphenoid is rounded beneath, bluntly pointed 

 anteriorly, where it hardly projects beyond the pars plana of either 

 side. Vomer is much as we find it in Falco, but a palatine is 

 peculiar, in that its prepalatine part is very slender and narrow, and 

 far separated from the corresponding part of the fellow of the 

 opposite side. The postpalatine portion is wide and spreading, with 

 its mesial borders abruptly, and with its remaining portion, less de- 

 flected downward. These palatine bones in some specimens hardly 

 meet each other in the median line, especially posteriorly, and this 

 state of things almost prevents the pterygoids from coming in con- 

 tact with the basisphenoidal rostrum. 



Posteriorly, a palatine is obliquely truncated from behind, for- 

 ward, and slightly rounded off at the angle. 



Carrying our investigations still further forward, we meet with 

 the same condition of the maxillary and the horizontal portion of 

 the maxillo palatine as was found in any of the genus Falco, but 



