140 



and form the four rounded angles of the platform sustaining the neural spine. The haemal 

 spine is a much-developed ' hypapophysis.' 



Neither the first, the second, nor the third vertebrae support pleurapophyses. The fourth 

 differs from the third in having a somewhat smaller hypapophysis ; but more markedly in the 

 shorter and thicker diapophyses, which support short, broad pleurapophyses, with expanded 

 and compressed extremities. The pleurapophyses of the fifth and sixth vertebra have a 

 similar form, with a slightly increased length : the expanded end of the sixth is more pro- 

 duced downwards. 



In the seventh vertebra the answerable lower angle of the pleurapophysis is much elongated, 

 and forms its continuation : the upper angle is reduced to a representative of the tubercle 

 of the rib. The tubercle almost disappears in the eighth vertebra, whose pleurapophyses 

 become simple, long, slender, with a sigmoid curve, but yet have no communication with 

 sternal ribs or sternum. The proximal ends of all the pleurapophyses have four equidistant, 

 sharp, longitudinal ridges ; those of the ninth vertebra are joined by short and slender semi- 

 ossified haemapophyses to the outer angles of a broad rhomboid sternum. Both pleur- and 

 haem-apophyses of the tenth to the thirteenth vertebrae progressively increase in length ; the 

 hsemapophyses of the last two of these vertebrae joining together before they unite with the 

 posterior angle of the sternum, the united parts representing a xiphoid prolongation of that 

 bone. The hsemapophyses of the fourteenth and some succeeding vertebrae complete the 

 haemal arch by uniting together, without the intervention of a haemal spine or sternal bone. 



Hunterian. 

 656. The skull of the black Scink (Cyclodus niger). 



The frontal and parietal bones are thick and expanded ; the parietal is bifurcated behind, 

 and articulated with the mastoids and paroccipitals. The postfrontals are separated from 

 the malars by the squamosals, which extend between the malars and the mastoids to form the 

 strong lateral bony arch resting anteriorly upon the malar and the maxillary, and posteriorly 

 on the parietal and tympanic. Concomitantly with this strong osseous roof of the cranium, 

 there is a singular arrest of development of bone in the fibre-membranous neurapophysial 

 walls of the cranium ; two lateral processes extend downwards into these walls from the 

 parietal and forwards from the exoccipitals ; but the sole trace of alisphenoids is seen in the 

 columnar bones, called 'columellee' by Cuvier, which extend from the interspaces of the 

 processes above mentioned, to rest upon the upper groove of the pterygoids. The orbito- 

 sphenoids are represented by still more slender bony styles, which circumscribe the outlets 

 for the optic nerves and form the anterior boundary of the prosencephalic division of the 

 cranium. The lachrymal bones are large and divided on each side, as in most Lizards. The 

 premaxillaries are confluent, and their nasal process separates the external nostrils from each 

 other. There are ten teeth or alveolar depressions in the premaxillary, which are minute and 

 pointed : the maxillary teeth are large and with hemispheric crowns, whence the name of the 

 genus. Each pterygoid presents a rough surface towards the palate, but does not support 

 teeth. There is a small ossicle between the pterygoid processes of the sphenoid and the true 

 pterygoid bones. The columelliform stapes is extremely long and slender. 



Hunterian. 



