494 MR. R. LYDEKKER ON SCELIDOTHERIUM. [Nov. 16, 



The only other part of the skeleton to which I wish to call 

 attention is the astragalus, and I have accordingly figured the type 

 specimen in Plate XLIX. fig. 3. It will be seen from this figure that 

 the external trochlear ridge for articulation with the tibia is not 

 prominent, and scarcely projects above the level of the internal 

 tuberosity. The astragalus (B.M. No. 37476) associated with the 

 cranium No. 37308 exhibits precisely similar features, although it 

 is of somewhat larger dimensions. This type of astragalus is very 

 widely different from that of Megatherium (in which the external 

 trochlear ridge is extremely prominent), and apparently indicates 

 that the eversion of the foot was not so great as in that genus. 



SCELIDOTHERIUM BRAVARDI, U. Sp. 



This species is founded on an imperfect skeleton in the British 

 Museum, brought by Bravard from the Argentine Republic, which 

 presents features clearly showing that it cannot belong to the type 

 species, to which it has hitherto been referred. The cranium (B.M. 

 No. 37626), which lacks the whole of the dentition and the greater 

 portion of the nasals, has been figured by Sir R. Owen in the ' Philo- 

 sophical Transactions' for 1857, pi. viii. fig. 2, from the palatal 

 aspect \ and referred to the type species ; an upper view is given in 

 Plate XLVII. of the present memoir. It is extremely unfortunate 

 that the nasals are wanting ; but from the structure of the adjacent 

 bones it can be shown that these bones were certainly much shorter 

 than in S. leptocephalum, since in the first place the superior border 

 of the facial portion of the maxilla forms a much shorter curve than 

 in the latter, while if the nasals were of the same length as in that 

 species they would have projected far in advance of the premaxillae. 

 That the nasals were of a shorter type is also evident from a com- 

 parison of the figure with that oi S. chiliense (Plate XL VIII.), when 

 it will be seen that the facial portion of the maxilla is not dissimilar 

 in the two species. The whole cranium is, moreover, relatively 

 narrower than in S. leptocephalum, and the frontal profile is quite 

 straight ; while only a narrow moiety of the facial portion of the 

 maxilla appears on the frontal aspect ; and the lachrymal is charac- 

 terized by its extreme prominence, and the partially upward direction 

 of the aperture of its canal. The anterior border of the zygomatic 

 process of the maxilla is nearly vertical, while the fronto-parietal 

 ridges are closely approximated, and the interdental portion of the 

 palate (as is well shown in Sir R. Owen's figure) is of excessive 

 narrowness. It will also be seen from the following table of dimen- 

 sions that while the width of the occipital condyles is smaller than 

 in S. leptocephalum, the interval between the condyles and the last 

 tooth is considerably greater, which indicates a great difference in 

 the relative proportions of the two crania. The premaxillse are well 

 developed. 



In the mandible ^ associated with the cranium, while the length of 



' The teeth have been introduced on one side in this figure. 



^ This specimen is figured by Owen, op. oit. pi. viii. figs. 4, 5, with the teeth 

 restored ; and apparently in pi. ix. figs. 2, 3, the specimen represented in fig. 2 

 being erroneously described as belonging to the upper jaw. 



