410 SKELETON OF THE FOWL. 



outer side of the optic foramen, and sometimes 

 confluent with it. 



d. The dorsal surface of the cranium. 



The dorsal surface of the cranium is rounded, 

 and formed almost entirely by the parietal and 

 frontal bones. It is broad behind, narrower in 

 front; and separated by a sharp almost trans- 

 verse line from the facial part of the skull. 

 The anterior ends of the frontal bones diverge 

 slightly from each other, and allow the meseth- 

 moid to come to the surface between them. 



2. The facial portion of the skull lies below and in front of 

 the cranial portion, with which it is only loosely 

 connected. It consists of (1) the olfactory capsules, 

 and the bones associated with them ; (2) the skeletal 

 elements of the jaws, and the hyoid apparatus. 



a, The olfactory capsules and associated bones. The 



olfactory capsules themselves remain in a car- 

 tilaginous condition throughout life, and are 

 therefore absent in macerated skulls. They are 

 separated only by a thin vertical septum, and 

 almost completely fill the conical space which, 

 in the dried skull, lies between the anterior end 

 of the orbit and the tip of the beak. Each 

 olfactory capsule has its cavity complicated by 

 a spirally rolled lamina of cartilage, which projects 

 inwards from its outer wall. 



In relation with the olfactory capsules are the 

 following bones. 



i. The nasals are a pair of thin lamellar bones, 

 which cover the sides of the hinder ends of 

 the olfactory capsules. Behind, they are fused 

 with the anterior ends of the frontals : while 

 their anterior borders are divided by deep 

 notches into superior and inferior processes, 

 which embrace the external narial openings. 



