THE 



GEOLOaiCAL MAGAZINE 



No. XLVII.— MAY, 1868. 



I. — On Saubosternon- Bainii, and Pristerodon McKati, Two New 



Fossil Lacertilian Eeptiles from South Africa. 



By Professor T. H. Huxley, LL.D., F.R.S. 



President of tlie Geological Society of London : Hunterian Professor of Comparative 

 Anatomy in the Royal College of Surgeons, etc., etc. 



(PLATES XL, XII.) 



SOME time since Prof. T. Eupert Jones directed my attention to 

 a curious fossil in the British Museum, obtained by Mr. Bain 

 from Styl Krantz, Sniewe Berg, South Africa. The matrix is of the 

 same nature as that in which the Dicynodonts are so commonly found, 

 and exhibits the greater part of the skeleton, but unfortunately not the 

 skull, of a Lacertilian reptile, not more than seven or eight inches in 

 length. It is represented of the natural size in Plate XI., Fig. 1. The 

 trunk is about two and a half inches long, and appears to have 

 attained hardly more than one-third the length of the tail, which is 

 bent round into three-quarters of a circle, and consists of vertebrae, 

 which are \Qry stout near its root, but become attenuated at its 

 termination {a). The centra of these vertebrse appear to have been 

 slightly constricted in the middle, and are about one-tenth of an 

 inch in length. The anterior caudal vertebrse present strong and long 

 transverse processes. The dorsal vertebrae can hardly have been 

 fewer than eighteen or twenty, and seem also to have possessed 

 hour-glass shaped centre. They are for the most part provided with 

 long curved ribs, the hindermost four or five pair of which become 

 gradually shorter. One or two vertebrae in front of the sacrum may 

 have been devoid of ribs. 



Both the fore and the hind limbs are in place, though but im- 

 perfectly preserved The impression of the large semilunar coracoids 

 (Figs. 1 and 2 6) which meet, and perhaps overlap in the middle line, 

 is very distinct. But one of the most interesting features of the fossil, 

 and that which best indicates its relation with the typical Lacertilia, is 

 the great T-shaped, or rather crossbow shaped, episternum or inter- 

 clavicle (Figs. 1 and 2, c), which in its general form and properties 

 closely resembles that of the existing Monitors. The clavicles them- 

 selves are not to be distinctly made out. The humerus is equal to 

 about 7 vertebree in length, and possesses a cylindrical shaft, which 



YOL. v. — NO. XLYII. 14 



