. Bulletin of the Natural History Museum Zoology. 156 ARNOLD. Fig. 1 Head and skull of Holaspis. a. Head from above; b. Head from side; c. Skull from above; d. Skull from side, fn frontonasal scale, fp frontoparietal suture, pa palpebral bone, pm premaxilla, r rostral scale, io inferior orbital foramen, so supraocular osteoderms, t triangular scale covering area occupied by interparietal and paired frontoparietal scales in most other lacertid lizards. a full impression of the extent of the dorsoventral flattening, largely because in fixed material shrinkage of the jaw muscles pulls the ki
. Bulletin of the Natural History Museum Zoology. 156 ARNOLD. Fig. 1 Head and skull of Holaspis. a. Head from above; b. Head from side; c. Skull from above; d. Skull from side, fn frontonasal scale, fp frontoparietal suture, pa palpebral bone, pm premaxilla, r rostral scale, io inferior orbital foramen, so supraocular osteoderms, t triangular scale covering area occupied by interparietal and paired frontoparietal scales in most other lacertid lizards. a full impression of the extent of the dorsoventral flattening, largely because in fixed material shrinkage of the jaw muscles pulls the kinetic skull into its most retracted position in which the vertical extent is greatest (Arnold 1998a). Also, unlike other lacertids, the whole of the limbs and tail are depressed in Holaspis. Head. The parietal area of the head (Fig. la, b) is flat and unarched and the snout is flattened above, being wedge-shaped in lateral view. The rostral shield is large, extending far on to the top of the snout and contacting the frontonasal scale very broadly. The nostrils are placed on the sides of the snout and are set well back from its tip. The area of the top of the head usually occupied by the interparietal and paired frontoparietal scales in other lacertids is covered in Holaspis by a single large triangular scale. The lower eyelid has a 'window' composed of enlarged semi-transparent scales. In H. guentheri these number 1-5 (mean , n = 15) while in H. laevis there are usually 2-4 (mean , n = 8) that are sometimes black-edged. The scales on the temporal area vary in size: dorsally and posteriorly they are typically large and polygonal, whereas anteriorly they are much smaller and diagonally elongated, running backwards and downwards from behind the eye in irregular lines that are separated by somewhat expansible hinge regions. The low skull (, d) is more delicately constructed and thin- boned than in any other lacertid lizard and the roof of the parietal region is so flexi
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