igo ZOOTOMY. 



VIII. In the skull make out : 



33. The rounded brain-case, greatly encroached upon 

 in front by the large orbits or cavities for the eyes, and 

 continued in front into the slender tri-radiate beak. 



34. The foramen magnum (Fig. 47, f.m) a large 

 rounded aperture in the ventral wall of the hinder end of 

 the brain-case. 



35. The occipital condyle {o.c), a small hemispherical 

 elevation on the lower or anterior margin of the foramen 

 magnum. 



36. The lambdoidal ridge, a transverse ridge, a little 

 above and parallel to the upper border of the foramen mag- 

 num ; it serves for the attachment of some of the muscles 

 of the neck. 



37. In the young bird the foramen magnum is bounded 

 by four distinct bones, one ventral, the basioccipital {b.o), 

 one dorsal, the supraoccipital {s.d), and a pair lateral, 

 the exoccipitals {e.o); the supraoccipital is bounded above 

 by the lambdoidal suture {Ib.s), which separates it from 

 the parietals, and is represented in the adult by the lamb- 

 doidal ridge. 



38. A median longitudinal groove on the dorsal surface of 

 the skull, passing behind into a low ridge which unites with 

 the centre of the lambdoidal ridge : it marks the position of 

 the obliterated suture between the right and left parietals 

 and frontals, 



39. In the young bird the parietals {pa) and frontals 

 (fr) form two distinct pairs of bones, the former extending 

 a short distance forward from the lambdoidal suture, while 

 the frontals furnish all the anterior part of the roof of the 

 brain-case, and are continued forwards between the orbits, 

 to each of which the corresponding frontal furnishes a 

 supraorbital ledge. 



