ZEUGLODON OSIRIS. 
237 
C. 10018. Portions of a soinowliat dlstortod skidl, iiichidin^r tlu* oocipital ro^'ion and most of tlio 
roof as far forwards as the posterior ])ortion ol' the nasids. Figured on PI. XX. 
ligs. S, 8 A. The cast of the cranial cavity is described and lignred hy Pilliot Hmith 
in Proc. Uoy. Soe. vol. 71, P.lOd, p[). 322-381, fig. 2. 
Tins si)ecin)en, so far as it goes, seems to resemble closely that figured hy Stromer, 
but is slightly larger. The occipital condyles (cowr/.), 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.') ap[)ear to 
meet in the middle line above the foramen magnum, making a suture with one anothe.r 
about 2'5 cm. long. The snpraocci})ital {soc.) is deeply concave from side to side, owing 
to the great size of the backwardly directed lateral portions of the lamhdoidal crest {l.c.), 
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 frontals, which is about 5 cm. behind 
the great supraorbital expansions of those bones. Laterally, the })Osterior portions of 
the parietals form part of the very slightly convex cranial Avails, and unite with tin; 
scjuamosals in a suture running downwards and forwards. The S(piamosals (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 {zt/g.) is large, and 
from its upper edge a ridge runs upwards and becomes continuous above with the 
lambdoidal ci'est, forming with it the posterior boundary of ihe enormous temporal 
fossa. The glenoid surface is wide and concave from before backwards ; there i^; 
a fairly well-developed postglenoid process. The frontals 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 (na.), which are thrust between or over them, 
and terminate behind in a sharp median angle. Of the nasals only the posterior 
])ortion 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 at zygomatic processes 82 
„ of occipital surface 22 
„ ,, condyles 6‘7 
,, of foramen magnum 8 
Heiglit of occipital surface above foramen maguum .... 18'5 
Length of sagittal crest of parietals 18 
Greatest width of nasals -t'S 
M. 8150. Plaster cast of the above specimen. A/ade in the /Aeilisli Muaentn. 
M. 8150 a. Plaster cttst of the cranial cavity of the above specimen. Figured Proc. Roy. Soc. 
vol. 71 (11)03) {). 325, fig. 2. AJade in the Jhiti.^h Alnseum. 
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 (Paheont. Abhandh, 
n. s., vol. i. p. 191, pi. XXX.) in his original description ol this species. In addition 
