1904.] LABYRINTHODONT SKULLS, 171 



The sutures between the roof-bones in the hinder half of the 

 skull are clear on both sides of the fossil ; but the elements in 

 the rostral region cannot be distinguished. There are the usual 

 two pairs of small bones forming the occipital margin between 

 the auditory notches, the middle pair being larger than the lateral 

 pair. The parietal bones (pa.) are a symmetrical pair-, twice as 

 wide in their posterior half as in their anterior half, and trun- 

 cated in front where they meet the f rentals {fi\). Their maximum 

 width is less than their total length, and the pineal foramen is 

 situated at their middle point. The frontals just enter the rim 

 of the orbit at its antero-internal portion ; but the parietals are 

 completely excluded from this rim by the antero-posteriorly 

 elongated postfrontals {ptf.). The squamosal element (sq.) is 

 longer than broad, articulating in fi'ont chiefly with the post- 

 orbital, but also meeting the postfrontal. The postorbital {pto.) 

 forms the posterior and half the externo-lateral rim of the orbit ; 

 the jugal [j.) enters the outer portion of this rim ; while the 

 prefrontal (prf.) completes it in front. The large prosquamosal 

 (jysq.) is about two-thirds as deep as long, tapering to a point 

 forwards. The quadrato-jugal ((y.) is about two-and-a-half times 

 as long as deep, also tapei-ing to a point forwards, and extending 

 slightly downwards below the level of the tooth-bearing edge of 

 the upper jaw. The jugal (j.), as usual, is irregularly triangular 

 in shape, with the radiating ridges of its ornamentation pre- 

 dominant. 



At the rostral end of the fossil represented in Plate XL, the 

 cranial roof and underlying matrix are I'emoved to expose the 

 palate from above. The antero-posteriorly elongated posterior 

 nares (ptn.) are thus well seen ; and the hinder edge of the large 

 premaxillary vacuity (pv.) is also preserved. The posterior limit 

 of the premaxilla [jyinx.) is distinct on the left side. The exten- 

 sive vomerine plates (v.), divided by a median suture, are also 

 well preserved. The premaxillary teeth, shown in transverse 

 section, are small, uniform in size, and arranged in close series. 

 The maxillary teeth, exposed in side view, are similar. Each 

 tooth appears to have been a hollow cone with plicated walls. 

 An excavation in the sandstone reveals hollows left by the decay 

 of the usual large teeth, which occur on the palate in front of and 

 behind the posterior narial openings. 



As already mentioned, the most interesting part of the skull is 

 the occipital region, which is especially well preserved (fig. 2). 

 It does not project sufficiently far backwards to admit of the 

 occipital condyles being seen when the cranium is viewed dii'ectly 

 from above. The position of the foi-amen magnum (fm.) is clear; 

 while a vacant space (socc.) between this and the roof-bones of 

 the occipital border suggests that a supraoccipital element was 

 present but unossified. Below the middle of the foramen magnum 

 there is a narrow tongue of bone (bocc.) separated by a little 

 matrix from the prominent occipital condyles. This is probably 



