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Show G MR. F. E. BEDDARD ON THE CRANIAL [Jan. 17, by him is Uromastix spinipes, or that in the particulars to be referred to there is no difference between U. spinipes and other species of the genus. In Uromastix, Gegenbaur figures a rather smaller postorbital than in Iguana, and represents the postfrontal of the latter lizard as absent. This interpretation of the bone bounding the orbit posteriorly and intervening between the jugal and the parietal is, I believe, correct; but, as will be seen from the annexed figure (text-fig. 2, p. 5), the postfrontal is not absent. The postfrontal is a very much smaller bone, both actually and relatively, than it is in a skull of Iguana tuberculata at my disposal. Furthermore, the postorbital in Uromastix spinipes has not the shape that it is represented to have in the drawing of Gegenbaur. It extends backwards along the jugal for a much greater distance, but does not, as is the case with the postorbital of Iguana, reach the squamosal. The squamosal in Uromastix spinipes requires some consideration since it appears to differ greatly from that of the Uromastix figured by Gegenbaur, and, indeed, from the squamosal of other Agamid lizards. There is, however, a likeness to the conditions obtaining in Iguana, a fact which encourages me in adopting a different view. The bones in question are depicted in the accompanying drawing (text-fig. 2, p. 5). As in other Agamids, the squamosal is a bifid bone, of which one limb is applied to the jugal and the other to the parietal. Posteriorly the squamosal is in contact with the quadrate and appears to be in contact also with the lateral process of the occipital. The whole of this bone is not however, as I think, to be regarded as squamosal. It is true that the examination of this region in the skull of some Lizards might lead to that inference. But in Uromastix (at any rate in U. spinipes) (text-fig. 3) the posterior undivided region of the bone in question is seen to be divided off by a suture, which is equally clear on both sides of the skull. The piece thus cut off from the supposed squamosal is in contact with the quadrate below and with a small bonelet laterally, to which reference will be made immediately, and which interposes between it and the lateral extension of the occipital. Text-fig. 3. Hack view of the skull figured on p. 3. HL2, second sui>ra temporal; other lettering as in text-fi: |