1 4 o 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 (o.c). 



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.e). 



