1900.] GitYroTHERiuM (neomylodcw) listai. 67 



skull, but its state of preservation is a little different from that of 

 the two specimens just described. It has clearly been buried in a 

 powdery deposit, which has stained it brown ; but the enveloping 

 dust must have been extremely dry, for fragments of cartilage 

 adhere to it, as well preserved as in the nasal chamber of the 

 cranium itself (no. 1). It also bears traces of the integument. 



Judging by the figures of the skull of Grypotheriwn published 

 by Bernhardt (loc. cit.), this specimen seems to have occupied the 

 anterior position in the nasal region represented in PI. V. fig. 3. 

 It is thus of great interest, because the three known skulls of 

 Grypotherium leave the precise nature of the bony arcade separating 

 the narial openings undecided. According to Bernhardt, the nasal 

 bones terminate as in Mylodon, and the arcade is an element 

 interposed between them and the premaxilla?. According to 

 Burmeister, the nasals themselves extend forwards and constitute 

 the greater part, if not the whole, of the problematical bar. The 

 fragment now under consideration is clearly in favour of the latter 

 interpretation. Its lower thickened end (a?) is a massive bone, 

 not bilaterally symmetrical, and not showing any trace of a median 

 suture. Its inferior face is irregular and roughened, and can 

 scarcely be regarded as an articular facette. Its upper portion 

 consists of a pair of bones (na.), separated by a very well-marked 

 median longitudinal suture. These are not thickened at their 

 contracted upper end, where they have evidently been broken, and 

 are not quite bilaterally symmetrical. They doubtless fuse at 

 their lower end with the problematical azygous bone already 

 mentioned, but the arrangement is obscured by the enveloping 

 soft parts. A pair of bones, which may be regarded as nasals, 

 thus extend forwards in a narrow arch to a point just above the 

 anterior end of the premaxillae ; while the massive bone effecting 

 a union between the two normal pairs of elements is probably an 

 ossification in the internasal septum. It is interesting to note 

 that there is an incipient trace of a similar forward production of 

 the nasals in the genus Scelidotherhim ; while there is sometimes 

 an ossification of the internasal septum in Megatherium \ 



The three specimens now described, when placed approximately 

 in their natural positions, as in the drawing (PI. V. figs. 1-3), afford 

 a very satisfactory idea of the form and proportions of the skull 

 when complete. The malar bone is the only important part to be 

 added; but unfortunately it is impossible to decide which of the 

 three specimens of this element in the collection belongs to the in- 

 dividual now under consideration. As already mentioned, these 

 three bones are all different in the shape and proportions of the 

 hinder bifurcated end. They are all very fresh in appearance, but 

 have been stained reddish brown by the earth in which they must 

 have been buried. The best example, from the right side, is shown 

 of one-half the natural size in the drawing (PI. VI. fig. 1). One 



1 R. Lydekker, Anales Mas. La Plata— Paleont. Argentina, vol. iii. pt. 2 

 (1894), p. 73, pi. xh. fig. 1. 



