ZEUGLODON OSIEIS. 237 



C. 10018. Portions o£ a somewhat distorted skull, including the occipital region and most of the 

 roof as far forwards as the posterior portion of the nasals. Figured on PL XX. 

 figs. 8, 8 A. The cast of the cranial cavity is described and figured by Elliot Smith 

 in Proc. Roy. Soc. vol. 71, 1903, pp. 322-331, fig. 2. 



This specimen, so far as it goes, seems to resemble closely that figured by Stromer, 

 but is slightly larger. The occipital condyles (cond.), which project considerably, 

 are relatively small ; they are widest at their upper end, and are strongly convex from 

 above downwards, but much less so from side to side. The exoccipitals {exo.) appear to 

 meet in the middle line above the foramen magnum, making a suture with one another 

 about 2-5 cm. long. The supraoccipital {soc.) is deeply concave from side to side, owing 

 to the great size of the backvvardly directed lateral portions of the lambdoidal crest {I.e.), 

 of which it forms the posterior face, the anterior being constituted by the expanded 

 posterior portion of the parietals {pa.), which unite with the supraoccipital in a very 

 deep suture, the outer line running along the edge of the crest. In front of the 

 lambdoidal crest, the upper part of the parietals forms a very high, sharp, sagittal 

 crest [s.c.) extending as far as their junction with the frontais, which is about 5 cm. behind 

 the great supraorbital expansions of those bones. Laterally, the posterior portions of 

 the parietals form part of the very slightly convex cranial walls, and unite with the 

 squamosals in a suture running downwards and forwards. The squamosals {sq.) are 

 very large, and their upper surface is convex from before backwards ; they form a 

 considerable part of the cranial wall. The zygomatic process [zyg-) is large, and 

 from its upper edge a ridge runs upwards and becomes continuous above with the 

 lambdoidal crest, forming with it the posterior boundary of Ihe enormous temporal 

 fossa. The glenoid surface is wide and concave from before backwards ; there is 

 a fairly well-developed postglenoid process. The frontais are incomplete, but it 

 can be seen that they formed the great supraorbital expansion usual in the genus. 

 In front they are separated by the nasals (iia.), which are thrust between or over them, 

 and terminate behind in a sharp median angle. Of the nasals only the posterior 

 portion is preserved : together they are convex from side to side and project a little 

 above the rest of the surface of the snout. The whole of the front and base of this 

 skull is wanting. The approximate dimensions (in centimetres) are : — 



Width ab zygomatic processes 32 



„ of occipital surface 22 



„ ,, condyles 6-7 



„ oE foramen magnum 3 



Height of occipital surface above foramen magnum .... 13".5 



Lengtrh of sagittal crest of parietals 13 



Greatest width of nasals 4"8 



M. 8150. Plaster cast of the above specimen. Made in the British Aluseum. 



M. 8150 a. Plaster cast of the cranial cavity of the above specimen. Figured Proc. lioy. Soc. 

 vol. 71 (1903) p. 325, fig. 2. Made in the British Museum. 



C. 10207. Left ramus of mandible wanting the angular and articular regions (text-fig. 77). This 

 specimen is almost exactly like that described and figured by Dames (Palaeont. Abhandl., 

 n. s., vol. i. p. 191, pi. XXX.) in his original description of this species. In addition 



