(lamina epiotien) >f, stands down and medially beyond the 

 general contour [57, fig. 49], this lodges the lower arm of a 

 three rayed sulcus (sulcus rcslilmbn-is epioticus)[7] which 

 in the recent state is converted by cartilage into the epiotic 

 vestibular recess. Behind the opisthotic there is on each 

 lamina an articular surface [8] for the supraoccipital ramus 

 of the exoccipital. 



The Opisthotic (Os opisthoticum) [Figs. 28 and 29] is a 

 wedge shaped bone, which in the articulated skull is inter- 

 posed obliquely between the exoccipital and the quadrate. 

 The oval exoccipital surface [1] occupies the greater part 

 of the postero-inferior aspect of the bone, the somewhat 

 larger quadrate surface occupies nearly the whole of the 

 antero-superior surface. Superiorly the bone shares in 

 forming the floor of the temporal fossa; inferiorly [2] it 

 forms portion of the roof of the acustico-jugular cavity. 

 The outer end of the inferior surface, just where it forms 

 the angle with the vertical outer margin of the bone gener- 

 ally presents a more or less well marked tubercle (tuber- 

 vuliini capiti-plastraUs) [3] to which the main portion of 

 the tendon of the capiti-plastralis muscle is attached. The 

 inner end of the bones presents surfaces for articulation 

 with the supraoccipital [4] and prootic bones [5]. It is also 

 excavated to form the opisthotic vestibular recess (recessus 

 vestibularis opisthoticus) [6] with which the posterior 

 vertical [7] and horizontal [8] semicircular canals commui- 

 cate. Immediately below the recess, the bone is perforated 

 by the glossopharyngeal canal [9]. A small flat tongue of 

 bone extends down from the body just below and in front 

 of this last canal, this interfenestral process [10] forms 

 with the body the boundary of a well marked though small 

 notch [11] behind, the upper half of the fenestra rotunda, 

 which in the recent state is completed by cartilage. 



The Prootic (Os prooticum) [Fig. 30] of very irregular 

 shape articulates with quadrate, pterygoid, basisphenoid, 



