I40 ZOOTOMY. 



while the second is a small sickle-shaped bone, closely 

 applied to the outer surface of the external process of the 

 parietal. 



52. The squamosal, a similar bone to the second or 

 hinder post-temporal : it lies external to the latter and 

 beneath the first post-temporal, which must be removed to 

 show it. 



53. The quadrate, a stout bone articulating dorsally 

 with the parotic process, and furnishing at its distal end the 

 glenoid surface for the articulation of the mandible : it is 

 strongly curved, convex anteriorly, and hollowed out behind. 



54. The basioccipital (Fig. 35, b.o), a median bone 

 forming the posterior part of the basis cranii, and furnishing 

 the middle third of the occipital condyle {ox). 



55. Large paired bones forming the lateral boundaries 

 of the foramen magnum, furnishing the outer thirds of the 

 occipital condyle, and continued outwards as the parotic 

 processes : each consists of the ankylosed exoccipital, (e.o) 

 (posterior portion), and opisthotic {op.o) (anterior portion). 



56. A median bone completing the foramen magnum 

 above, and continued upwards as the vertical sagittal 

 crest to the parietals : the median portion of this bone is 

 the supraoccipital {s.o), its lateral portions represent the 

 epiotics {ep.o.). 



57. The prootics {pr.o), paired bones continuing for- 

 wards the combined exoccipitals and opisthotics with which 

 they articulate posteriorly, thus forming the anterior half of 

 the side walls of the brain-case : above they articulate with 

 the epiotics. 



58. The pro-, epi-, and opisthotics together form the 

 auditory capsule : the cavities for the three semi- 

 circular canals can be seen through them (Fig. 37, a.s.c, 

 p s.c, h.s.c). 



