the Homologies of the Lizard's Skull. 93 



clear in the specimen. The middle of the l)one articulates 

 with the inner part of the head of the quadrate ; its rela- 

 tions (if any) to the paroccipital cannot be made out. The 

 anterior limb of the bone passes forwards below the temporal 

 fossa, to be overlapped l)v the postorbital. 



The quadrato-jugal (Qu.J.) is a small bone covering the 

 whole of the outer edge of the quadrate, but not covering its 

 head at all. Its upper end is covered by the postorbital and 

 l)art of its front margin by the jugal. 



Tbcquadiate (Qu.) is a remarkable bone; it is very short and 

 broad, nearly square when viewed from behind. Its lower 

 edge lias the usual grooved articulating surface. The inner 

 edge of the bone has a strong rounded ridge running verti- 

 cally, outside which there is a deep pocket on the posterior 

 surface. Except for the fact that its outer border is covered 

 by a quadrato-jugal, it very strongly recalls the quadrate of 

 an Agamid. 



Of the palate very little can be said ; there are obviously 

 large posterior nares and very large suborbital vacuities, and 

 the specimen suggests very strongly that the transverse bones 

 are lost. 



Judging from Lortet's figure and some casts, the skull of 

 Sauranodon {Sapheosaurus) seems to resemble that of Pleuro- 

 saurus described above in the condition of the temporal 

 region. With the exception of Boulenger, all recent authors 

 seem to have regarded these reptiles as Rhynchocephalia 

 closely allied to Sphenodon. Boulenger *, speaking of 

 Lortet's figures of Pleurosaurus, says : — " It is, however, 

 quite clear that the cranial characters are not Rhyncho- 

 cephalian. The temporal arch appears to be essentially of 

 a Lacertilian type and to correspond with what is found in 

 the Agamidse." This statement seems to rae to be still 

 essentially true. The fact, definitely shown in Lortet's 

 figures as well as in the British Museum specimen, that 

 there is only a single temporal vacuity, is conclusive that 

 the form is not a Rhynchocephalian. If the temporal bones 

 of a lizard are interpreted as I have done above, the con- 

 dition of the arch is really strikingly similar to that in such 

 an Agamid lizard as Chlamijdosaunis , whose arch can be 

 simply derived from it by the reduction of the anterior limb 

 of the squamosal (that which meets the postorbital) and the 

 retreat upwards of the quadrato-jugal in accordance with the 



* Ann. & Mag. Nat. Hist. ser. 6, vol. xi. p. 208 (1893). 



