376 me. r. w. hooley on the [June 191 3,. 



The Antorbital Vacuity. 



The antorbital vacuity (PL XXXVII, fig. 2, a.o.v.) is large, 

 elongately rhomboid, entirely separated from the orbit and the- 

 nasal opening. 



Antorbital Vacuity No. 2. 



An additional preorbital vacuity (PI. XXXVII, fig. 2, a.o.v. 2) 

 is situated in front, beneath, and confluent with the orbit. It is 

 shuttle-shaped, obliquely placed, and bounded by the jugal above 

 and the quadratojugal beneath. In a profile view of the skull its- 

 width appears much less than it is in reality. 



The Orbit. 



The orbit (PI. XXXVII, fig. 2, 0.) is small, circular, and placed 

 very far behind the mandibular articulation. Except the narrow 

 opening into the antorbital vacuity Xo. 2, it is entirely surrounded 

 by bone. The anterior margin is formed by the extreme proximal 

 end of the jugal and a moiety of the lachrymal, the roof by the- 

 prefrontal and the frontal, and the posterior border by the post- 

 frontal and postorbital: that is, if we take this buttress to 'include 

 both these elements, as in Sphenodon.'' x Its lower boundary is 

 formed entirely by the quadratojugal, which here is hollowed as 

 far as the anterior region of the orbit, where a broadening of the 

 bone determines the extent of, but does not complete, the orbital, 

 rim. There was no trace of a sclerotic ring. 



The Snpra-Temporal Fossa. 



The supra-temporal fossa (PI. XXXVII, fig. 3, s.t.f.) is deep,, 

 large, and thrown open laterally, because of the supra-temporal 

 arcade rising obliquely forward from the lowest point of the outer 

 edge of the back of the skull. It is bounded on its posterior and 

 lower borders by the squamosal and a process from that bone, and: 

 anteriorly by the post-fronto-orbital buttress. 



The Infra-Temporal Fossa. 



The infra-temporal fossa (PI. XXXVII, figs. 2 & 3, i.t.f.) is- 

 large, directed obliquely, and extends in front of and behind the 

 orbit for equal distances. It is bordered above by the squamosal 

 bar and the quadratojugal, and below entirely by the quadrate. 

 The inner hinder border of these bones forms a rising floor under 

 the posterior end of the vacuity, which prevents its full extent 

 from being observed in a profile view. 



1 E. T. Newton, Phil. Trans. Eoy. Soc. 1887, ser. B, vol. clxxix 

 p. 506. 



