90 THE NATURAL HISTORY EEYIEW. 



blades "by one broad triangular in outline, the anterior cusp and the 

 inner tubercle, eacb by a cylindrical incurved one, that of the former 

 being tbe smaller. The posterior blade is almost equal in antero- 

 posterior extent to the anterior cusp and the anterior blade, and 

 according to Cuvier* is sometimes larger than in H. crocuta. The 

 blades are separated from each other by a deep cleft. 



In the same traus verse line with the posterior blade, and on the 

 inner side is the upper true molar. In the two specimens which have 

 passed through my hands from "Wookey Hole, it is very small, equi- 

 lateral-triangular, and supported by two fangs of which the anterior 

 and outer is by far the smaller. The posterior, supporting the two 

 posterior angles, is enclosed in an alveolus with very delicate walls, 

 which would soon disappear by absorption after the loss of the tooth. 

 M. De Blainville,t describes one tooth as perfectly round, and sup- 

 ported by one conical fang (" portee sur un racine unique, conique") ; 

 and then proceeds to cite the rounded form of the crown, as differen- 

 tiating the Spelaean Hyena from the recent H. crocuta^ in which it 

 is nearly triangular (subtriquetre). Professor Owen, following his 

 lead, infers from the presence of one alveolus only in the specimens 

 that have passed through his hands, that the tooth in question is 

 supported by one fang only, and then proceeds to quote this as addi- 

 tional evidence in favour of the specific difference between the two. J 

 On a careful examination of the skull of the Lawford Hyena in the 

 Eucklandian Collection, brought forward in evidence of the one- 

 fanged true molar, I failed to detect the least trace either of it or 

 its alveolus, on either side.§ The latter has been entirely obliterated 

 by absorption. That, however, the true molar of Spelaean Hyena 

 was sometimes supported by one fang only is proved not only by 

 fig. 57 in the Fossil Mammals, the history of which is not given, but 

 by a beautiful upper jaw in the "Williams Collection at Taunton in 

 which the alveolus is preserved. It is clear, therefore, that the upper 

 true molar of the Spelaean Hyena was sometimes one — at others bi- 



* Op. cit. p. 399- t Op. cit. p. 42. 



X Foss. Mam. p. 150. Fig. 57. 8vo. 1846. 



§ Professor Owen, (Op. cit. p. 149) indeed, seems to have laboured under 

 some mistake when he says : " The socket of the small tubercular or fifth molar 

 tooth is preserved on each side of this rare and beautiful cranium (the Lawford 

 skull), illustrating the character first observed by M. De Blainville in a fragment of 

 the upper jaw of a Jlycena spelcea from a continental locality, now in the Parisian 

 Museum ; viz. the small size and rounded form of the fifth or tubercular molar." Is 

 it possible to infer the form of the crown, from the shape of the alveolus ? 



