FOSSIL MAMMALIA. 75 



The condyles of the occiput (See PI. XXI. fig. 2,) are wide apart, sub-elliptic, very 

 similar in position, form, and relative size to those in Orycteropus. The foramen 

 occipitale is transversely oval, its plane slopes from above downwards and forwards 

 at an angle of 40° with that of the occipital region of the skull. This region, as 

 before stated, is vertical in position (see fig. 1, PI. XXI.), of a sub-semicircular 

 form, the breadth being nearly one-third more than the height ; it is bounded 

 above and laterally by a pretty regular curve ; but the superior margin is not 

 produced so far backwards as in Orycteropus. The occipital plane is bisected by 

 a mesial vertical ridge; there is a less developed transverse curved inter-muscular 

 crest which runs parallel with and about half an inch below the marginal ridge : 

 the surface of the occipital plane on the interspaces of these ridges is irregularly 

 pitted with the impression of the insertion of powerful muscles. The corres- 

 ponding surface is smooth in the Orycterope and Armadillos; in the great extinct 

 Glossothere it resembles in character that of the Scelidothere ; but in the forward 

 slope of the occipital plane the Glossothere differs in a marked degree from the 

 present animal. 



The upper surface of the cranium is smooth and regularly convex. The 

 extent of the origin of the temporal muscles is defined by a slightly-raised broad 

 commencement of a ridge, which, in the older animal, might become more de- 

 veloped. There is no trace of this ridge in the Orycterope ; but it exists in the 

 Armadillos, in which the teeth are of a denser texture, and better organized for 

 mastication, and consequently are associated with better developed masticatory 

 muscles. It will be subsequently shown that the Scelidothere resembles the 

 Armadillos in so far as it possesses a greater proportion of the dense ivory to the 

 externa] casmentum in its teeth, than does the Megatherium ; while it differs 

 widely from the Orycterope, in the structure of its teeth. The teeth, however, 

 are fewer in the Scelidothere than in any Armadillo, and relatively smaller 

 than in most of the species of that family. Accordingly we find that the 

 zygomatic arches are relatively weaker ; and in this particular the Scelidothere 

 corresponds with the Orycterope. The zygomatic process of the temporal 

 commences posteriorly about an inch and a half from the occipital plane, its 

 origin or base is extended forwards in a horizontal line fully four inches, where 

 it terminates as usual in a thin concave edge, as shown on the right side in 

 PI. XXII. The free portion of the zygoma, continued forwards from the outer 

 part of this edge, is a slender sub compressed process, half an inch in the longest 

 or vertical diameter, and less than three lines in the transverse ; the extremity of 

 this process is broken off; the opposite extremity of the malar portion of the 

 zygoma is entire, and obtusely rounded. The bony arch may have been com- 

 pleted by the extension of the temporal process to the malar one, but the two 

 parts undoubtedly were not connected together by so extensive a surface as in 



