98 FAUNA ANTIQUA SIVALENSIS. 



Another example is famished by a beautiful specimen ot 

 tinknown origin, m the British Museum, which consists of 

 three ridges and a talon appendage of two tubercles. The 

 two anterior ridges are slightly affected by wear, the last 

 being intact. One intermediate tubercle is developed in each 

 of the hollows alternately with the points of the outer divi- 

 sion. This specimen belongs to the left side of the lower jaw ; 

 it presents the characteristic ' gourd-shaped ' expansion at 

 the posterior extremity, and the dimensions correspond 

 exactly with those yielded by Lartet's Gers specimen — viz., 

 length, 4*5 ; width in front, 2*1 ; and behmd, 2*6 inches. 



The third, or last, inferior true molar (being the sixth in 

 antero-posterior succession) occurs along with the penultimate 

 in the Tournans lower jaw specimen abeady referred to.^ Tho 

 crown is divided into four ridges, with a large talon forming 

 a fifth and terminal ridge. The tooth is entire, and the 

 animal to which it belonged must have been aged, as the 

 three anterior ridges are well worn. The plane of the grind- 

 ing surface shows a considerable amount of concavity from 

 back to front, and the crown narrows very much towards its 

 posterior end, being the reverse of what is seen in the two 

 molars which precede it in position. The dimensions of this 

 tooth are — length, 7*25 ; and width in front, 3 inches. It 

 is figured by M. de Blainville, and enumerated in the refe- 

 rences as the fifth, or penultimate ; but it is described by him 

 as the sixth, or last, in the text devoted to the dentition of 

 M. angustidens, although the corresponding last tooth of the 

 upper jaw of the same specimen, and which, in fact, was 

 opposed to it in use, is described as the 'fifth,'^ The occurrence 

 of this last inferior molar in situ behind the penultimate, 

 taken in conjunction with the form and dimensions, furnish 

 conclusive proofs that this tooth is the third true molar of the 

 lower jaw; and the evidence yielded by the division of the 

 crown ridges is equally demonstrative that the species fi'om 

 which it was derived is distinct from the M. longirostris of 

 Eppelsheim, a conclusion which is further sui3ported by the 

 enormous elongation of the beak of the symphysis in the 

 lower jaw of If.- angustidens. 



The dental formula of the molars in M. angustidens appears, 



therefore, to have been "*" "^ milk molars ; t. ^ "*" pre- 

 molars ; and ,— -^j r true molars ; and the number of ridg-es 



in the different teeth, according to their succession, 



2 + 3 ? + 3 

 '2 + 3 ? + 3 



' De Blainville, Osteographie, pi. xiv. ^ Idciii, he. cit. p. 302. 

 and pi. XV. 



