168 BRITISH FOSSIL REPTILES. 



than in either of the bkmt- or thick-toothed Lacertians. I may remark, also, that, 

 as usual in the larger forms, the orbits are relatively smaller than in the dwarfed 

 kinds. 



In all the Lacertians here compared, teeth are developed from the whole 

 {Iguana, Tujpinamhis), or nearly the whole {Tlydrosaurus, Varanus), of the alveolar 

 border of the maxillary; consequently this dental series extends beneath both 

 nasal and orbital vacuities, but for a less extent in the carnivorous than in the 

 herbivorous Lacertians. Sclcidosaurns, in the degree and kind of its facial 

 ossification, repeats the mammalian character exemplified in Iijuanodon. 



Of the subjects of the present paper the first block of Lower Oolitic Freestone 

 includes a great proportion of the right side of the facial part of the skull (Plate 

 87, fig. 1). The missing parts are the fore end of the premaxillary (ib. 22') and 

 the hind or suborbital end of the maxillary (21') ; the upper and hinder pointed 

 termination of the facial process of the maxillary is preserved in articulation with 

 the prefrontal, /. 



The length of this facial fossil is 1 foot 3j inches ; its height from the upper 

 angle (a) of the maxillary process to the tip of the longest subjacent tooth, in 

 situ, is 9 inches. 



Of the premaxillary are preserved part of the nasal process (22'') and so much 

 of the alveolar part (22) as lodges two fully developed and protruded teeth and the 

 sockets of two others : an intervening part of the bone has been chiselled away to 

 admit a wedge for the quarryiug-operations ; the length of the preserved pre- 

 maxillary nasal process (22") is 4 inches, the breadth of its base is 1 inch : it 

 narrows to its apex, being limited to the fore and under part of the large bony 

 narial vacuity («,/) in the present specimen. 



So much of 22" as is preserved forms rather more than one third of the lower 

 border of the external nostril, the rest of that border with the hinder boundary (a) 

 being contributed by the maxillary (21, a). The suture between these bones is 

 distinct. 



The preserved length of the alveolar part of the maxillary (21, 21') is one foot : 

 the upper border of this part contributes to the large narial («) and in a less degree 

 to the orbital (0) vacuities ; but these portions of such tooth-bearing part of the 

 upper jaw combine to form the base of the facial process, which is between four and 

 five inches in extent : its breadth, at one inch above the border line (21, 2l')j is 

 3 inches ; this breadth is nearly preserved to the angle («), aboixt six inches above the 

 alveolar border, at which angle the maxillary is continued backward, above the 

 fore part of the orbit, gradually narrowing to a point, which joins the pre- 

 frontal. 



Much of the outer wall of the alveolar part of the maxillary adheres to the 

 block of freestone in which the counterpart of the above-described cranial fossil is 



