1886.] MR. R. LYDEKKER ON SCELIDOTHERIUM. 4!)5 



the symphysis is greater than in S. leptocephalum, the interval 

 between the hinder border of the symphysis and the first tootli is 

 very considerably less. The superior border of that portion of the 

 mandible in advance of the teeth is moreover inclined strongly 

 upwards. 



The following dimensions may be compared with those of S. 

 leptocephalum : — 



Length of facial part of maxilla (about) 0*135 



Width of the two occipital condyles 0*095 



Length from condyle to last tooth 0*258 



Length of upper dental series 0*105 



Length of mandibular symphysis 0*175 



Literval between hinder border of symphysis and 



last tooth 0-350 



Interval between do. and first tooth 0*032 



I will now direct attention to the astragalus. Unfortunately the 

 one specimen o£ this bone, associated with the cranium, is imperfect, 

 although sufficient remains to show that it differs from the corre- 

 sponding bone of the type species by the great prominence of the 

 external trochlear ridge, which projects far above the level of the 

 internal tuberosity. In Plate XLIX. fig. 4, there is represented an 

 astragalus from a cavern in Brazil, which, although of larger size 

 than Bravard's specimen, agrees precisely in structure, and either 

 belongs to a male of the present form or to an allied species ; and I 

 think a comparison of this figure with that of the astragalus of 

 (S. leptocephalum will leave no doubt as to the specific distinctness 

 of the two forms. This astragalus agrees precisely with the corre- 

 sponding bone of a hind foot belonging to a perfect skeleton figured 

 by Dr. Burmeister in the Monatsb. k. preuss. Ak. Wiss. for 18S1, 

 plate facing p. 380, fig. 2, and referred (on the authority of Sir R. 

 Owen's figure of the cranium of the present form) to a large male 

 of S. leptocephalum. A tibia from Brazil, associated with the 

 figured astragalus, presents a structure of its distal surface modified 

 to accord with this peculiar articulation, which is different from that 

 of the tibia of S. leptocephalum ; and there are equally well-marked 

 differences in some of the other bones of the present form to which 

 I shall allude on another occasion. 



Whether or no the larger bones mentioned above belong to male 

 individuals of the same species as the cranium, I think sufficient 

 evidence has been adduced to show that both the form to which 

 the latter and that to which the former belonged are specifically 

 distinct from 5. leptocephalum. 



Confining, however, attention to Bravard's specimen, it is quite 

 evident that this form is distinct both from S. tarijense (in which 

 the mandible is of quite a different type) aud S. {Flatyonyx) brong- 

 fiiarti (in which the nasals are very short and the premaxillae 

 aborted) ; and since it appears impossible to identify it with either 

 of the ill-defined Brazilian forms mentioned above to which specific 

 names have been assigned, I propose that it should be known as 



