FAUNA 01' TILE GOSAU EOllMAXION. 



631 



some little distance in advance of the basioccipital, which may be 

 presumed to penetrate the exoccipital bones and give passage to the 

 pneumogastric and hypoglossal nerves. The occipital condyle is 

 well rounded ; but its outline is sub trapezoidal ; its greatest width in 

 the upper third is 2 centim., its greatest depth 16 millim. The 

 under surface is deeply channelled, so that the thickness of the bone 

 behind the articular surface is one millim. The region in front of 

 the occipital condyle is about 3| centim. long, fairly smooth, but 

 concavely excavated in the middle, both in length and breadth, rising, 

 however, to a rounded margin at the sides internal to the lateral 

 foramina. The width across the pneumogastric foramina is 3 centim. 

 The lateral margin of the triangle is divided by a median convexity 

 into two concavities : the shorter, in front, is about 2 centim. long ; 

 and the longer, behind, is a little more; while posterior to this, on the 

 left side, is a surface which appears to have been laterally sutural 

 and nearly vertical, while a suture on the opposite side shows that 

 the upper part of this mass consists of a small bone, which readily 

 comes away. Hence I interpret the lateral masses of bone external 

 to the foramen magnum as being the exoccipital bones, as in Croco- 

 diles, while the small bone above the outer border of the exoccipital 

 is the paroccipital of Owen ; and I suppose the exoccipital to extend 

 forward so as to form the side of the wall of the brain-case ; so that 

 no portion of the posterior lateral structure preserved can be the 

 quadrate bone, as supposed by Biinzel, and hence the analogy 

 attempted to be made out in this region of the skull with the 

 Crocodile can have no foundation. 



I would next note the characters of the lateral aspect of the skull. 

 (PI. XXYII. rig. 5). Here all the bones which are connected with 

 the roof of the brain-case are more or less broken, and the bones have 

 disappeared which formed the external suspensory arch for the lower 

 jaw, so that nothing remains but the internal part of the head, 

 which may be likened, perhaps, to that of a Crocodilian type in 

 which neither were the quadrate bones blended with its lateral walls 

 nor the pterygoid bones connected with its base. I fail altogether 

 to recognize a Lizard-like type, although, as at present used, the 

 term Lizard is almost large enough to include any thing. Forms 

 like Amjohisbcena, which have the quadrate bone firmly wedged into 

 the skull and no trace of either of the postorbital arches, might well 

 be regarded as a distinct ordinal type ; and there are some Dinosaurs 

 towards which the structures of the hinder part of such a brain-case 

 somewhat approximates ; but the cranial bones in ordinary Lizards, 

 like Iguana, form a part of the skull that is very imperfectly con- 

 nected with its roof, and very different from the structure seen in 

 Crocodiles and Dinosaurs, though other Lizards, like Cnemidophoras 

 for instance, have a better union between the brain-case and the 

 surrounding bones ; but I do not recall any type of Lizard that so 

 far corresponds in the characters of the bones covering the brain 

 with what is seen in Dinosaurs as to justify us in affirming that this 

 skull is lacertilian. Turning our attention first to the basal part of 

 the brain-case, it will be seen that the articular head of the basiocci- 



