92 TUE XATUHAL HISTOEY REYIEW. 



The crown of Premolar 4, consists of a principal cone bisected by 

 trencbant ridges and mapped oiF from the two accessory cusps by a 

 cleft. Of tbe latter tbe posterior is by far tbe larger. On tbe inner 

 and posterior side is a broad excavation bounded posteriorly by a ridge. 

 The anterior of the two straight cylindrical fangs is slightly the 

 longer, the posterior is bevelled as it approaches the cervix of the 

 tooth to admit of the close apposition of the true molar on the inner side. 



In the lower true molar (M. 1.) the sectorial portion of the 

 crown is largely increased at the expense of the tubercular, which is 

 proportionally diminished. The anterior blade of the unworn tooth 

 is by far the largest. A slight ridge traverses its anterior base, 

 and is more pronounced on the outer than the inner side. On the 

 posterior aspect of the tooth a ridge descends down to the inner side 

 of the tubercular portion. This latter rising but little above the 

 level of the cingulum is variable in form and size to such a degree 

 that its variations have been deemed by eminent French Palseonto- 

 logists of specific value. So far as it is concerned the 18 jaws upon 

 the table before me as I write, fall into three groups. In the first, 

 represented by 8 jaws, its surface is traversed by a ridge which 

 passes obliquely from the posterior border to the descending ridge 

 of the posterior blade from which it is separated by a small cleft. 

 The faint ridge bearing small tubercles on the summit of the cingu- 

 lum is not cleft behind, nor is there any trace of a cusp at the inner 

 and posterior base of the posterior blade. This is the form most 

 common in the jaws of the Spelaean Hyena, and is that which MM. 

 Croizet, Jobert, Marcel de Serres, Dubrueil and Jeanjean have con- 

 sidered strictly typical. In the three jaws representing the second 

 group, the ridge on the tubercular portion is still present, stout in 

 two, scarcely marked in the third. At the point, however, where 

 it joins the descending ridge of the posterior blade, is a small well de- 

 fined cusp, separated by a cleft in one, by a notch in the remaining two, 

 from the blade (fig. 4 & 5). This is the form which Marcel de Serres, 

 Dubrueil and Jeanjean have named Hycena intermedia,* and con- 

 sidered representative of H. brunnea. M. De Blainvillef has met 

 with this form in a jaw from a foreign locality in the Jardin des 

 Plantes, and in a second from Kent's Hole. And lastly, two jaws are 

 characterized by the development of a stout cusp on the inner side 

 of the tubercular portion, which, together with the ridge, give it a 



* Tom. cit. p. 88. f Tom. cit. p. 40. 



