5S 



NEW YORK STATE MUSEUM 



united palatines seems to be complete, while its anterior extremity 

 is pointed and free. The maxillopalatines have already been fully 

 described above, their relation to the internasal septum and the 

 vomer can also be seen in figure 22,. 



The pterygoids are a very slender pair of bones in Circus ; an- 

 teriorly they articulate with the palatines and the rostrum of the 

 sphenoid, although they fail to come in contact with each other at 

 this point. Their posterior extremities are expanded and cup shaped 

 to allow them to articulate with a corresponding convexity on each 

 quadrate. They do not meet the basisphenoid by articulation with 

 basipterygoid processes, as in the Striges. At the points, however, 

 where such processes are developed, Circus possesses a sharp 

 pointed spicula of bone on either side, and this is opposite a 



Fig. 23 A vertical, longitudinal section of the skull 

 of Circus, made nearly in the median plane, designed 

 to show the capacity of the brain case, and the position 

 of the vomer, v. Life size by the author from his 

 own dissections 



corresponding enlarged part of each pterygoid [fig. 21]. These 

 two projections are separated from each other by at least two milli- 

 meters in life, i. e. the pointed rudimentary basipterygoid process 

 and the enlargement on the corresponding pterygoid. 



The basitemporal and basioccipital regions are well depressed 

 below the exoccipital regions and other surrounding parts [fig. 21]. 

 A thin lip of bone overhangs the two openings of the Eustachian 

 tubes, while the foramina for the internal carotids lie external and 

 posterior to them just above the anterior tympanic recess. The 

 foramina for the exit of the other cranial nerves that issue from 

 the brain case occupy their usual sites and ofl^er nothing peculiar for 

 description. They agree with Parker's figure of a nestling of 

 Accipiter nisus. 



