310 MR. E. LTDEKKER ON A MANDIBLE OF 



was identilied with the typical Yal d'Arno M. cultridens, first by 

 Kaup * and subsequently by Gaudry t , the identification having 

 been made solely from the comparison of the upper canines from 

 the Val d'Arno witb those from Eppelsheim and Pikermi. Dr. 

 Major t speaks of the Pikermi Maclicerodus (of which several jaws 

 are known §) as being closely allied to M. cultridens, but does not 

 enter into further details. Palconer || regarded M. latidens as un- 

 distinguishable from M. cultridens. In the Cat. Foss. Mamm. Brit. 

 Mus., I have followed Kaup and Gaudry's view, as I had at that 

 time no specimens which led me to doubt its accuracy %. In the 

 Pikermi and Eppelsheim form there are two elongated lower pre- 

 molars, and the diastema of the male is comparatively large. So 

 far as I can find out, no jaws of the typical Yal d'Arno form are 

 known ; and since all the other mammals from those beds are 

 distinct from the Pikermi and Eppelsheim species, there are prima 

 facie grounds for considering that the identification of the Pikermi 

 Machcerodus with M. cultridens is not fully certain. Macho^rodus 

 latidens has been hitherto known only by detached canines and 

 incisors, the upper canines being relatively broader than in 1\I, 

 cultridens. M. mcganthereon is a much smaller form, distinguished 

 by the absence of serrations on the upper incisors. 



Mr. Backhouse's specimen, which has lost the innermost incisors, 

 indicates a species about equal in size to the Pikermi Machcerodus, 

 and, from the large size of the concavity for the upper canine and 

 the descending mandibular flange, apparently belonged to a male. 

 There is only one premolar, which is of comparatively small size, 

 and from the sharpness of the alveolar border in front of this tooth 

 it is evident that pm. 3 was never developed. Compared with the 

 mandible of a male of the Pikermi Machcerodus **, the fossil differs 

 not only in the absence of pm. 3, but is absolutely shorter, and has 

 a relatively shorter and deeper diastema and a wider and shallower 

 concavity for the upper canine, while pm. 4 is relatively shorter. 

 These differences are shown by the following dimensions, the length 

 of mTT of the continental form being taken from the Eppelsheim 

 specimen B.M. No. 49967 a. 



Pikermi. Forest-bed. 

 Interval between canine and carnassial .... 0*098 0*069 



Length of carnassial 0*031 0*032 



Length of fourth premolar 0*027 0*0215 



* ' Neues Jabrb.' 1859, pp. 270-271. 



t ' Animaux Fossiles et Geologic de I'Attique,' pp. 105-109. 



i Quart. Journ. Geol. Soc. vol. xli. p. 3 (1885). 



§ See Cat. Foss. Mamm. Brit. Mus. pt. i. p. 43. 



II ' Palseontological Memoirs,' vol. ii. p. 459. 



^ The question of the long range in time of the species as thus extended 

 was not taken into consideration. 



^* See Cat. Foss. Mamm. Brit. Mus. pt. i. p. 43, no. 49674 (misprinted 59674). 

 In an immature female (No. 49674 bis) the diastema is shorter and the ramus 

 shallower; a specimen from Eppelsheim (No. 49967 «) has a similar short 

 diastema and no descending flange, and therefore probably also belongs to an 

 adult female in which the ramus is much deeper. 



