124 r. N. BOSE ON P08SIL CAKKIYOKA 



Leidy'S somewhat aberrant species (M. primcevus) *, there are alto- 

 gether three molars, the anterior false molar of Felis (pm. 2) being 

 absent. Now this tooth replaces the first milk-molar, that is to say, 

 the molar between the deciduous sectorial and the canine f. Hence, 

 as the anterior premolar of Felis is absent in the adult dentition of 

 Machcerodus, we should expect the corresponding molar of the milk- 

 dentition also to be absent in the latter. The anterior false molar 

 of the adult Machoerodus is the homologue of the second of the molar 

 series in Felis^ and, as in this genus, replaces the deciduous sec- 

 torial, the permanent sectorial taking the place of the large back 

 molar of the milk-dentition. Thus the deciduous dentition of the 

 upper jaw on each side in Machcerodus would be 



d.i. 3, d.c. 1, d.m. 2=6, 

 instead of 



d. i. 3, d. c. 1, d. m. 3 (Felis)=7. 



There are two other points in Prof. Owen's description which call 

 for a word or two by way of comment. He says that the " inner 

 tubercle of the sectorial is less developed than in the normal species 

 of Felis J' But it is not developed at all. Both edges of the canine 

 are asserted by the eminent naturalist to be ^' finely, but distinctly 

 serrated." The serration of the posterior edge is distinct, but 

 the anterior edge is damaged ; and we cannot determine whether 

 it was serrated or not. 



The other fragment of upper jaw (B.M. no. 39730) evidently 

 belongs to an adult individual, and exhibits three molars in situ. 

 The canine has been removed, and the hinder part only of its alve- 

 olus is visible. It is separated by a short diastema (0'35 inch) 

 from the anterior premolar, which is the homologue of the second 

 of the molar series in Felis. It is two-fanged, the fangs being 

 divergent. The crown has been damaged ; but the base shows 

 the tooth to have been smaller than the corresponding tooth of M. 

 neogceus, as well as of M. meg anther eon. The sectorial is interme- 

 diate in size between these two species ; in antero-posterior length 

 it is a little less than double the deciduous sectorial, and is much 

 more* stout and less trenchant than the latter. There is no internal 

 tubercle, but a slight thickening of the cingulum is visible in its 

 place ; and a prominent flattened ridge (absent in the milk-sectorial) 

 ascends from the thickened portion to the summit of the second of 

 the three lobes into which the blade is as usual divided. In the an- 

 terior of these lobes a notch maps off a small lobe in front and a 

 considerably larger one behind. The middle lobe has an elevated, 

 triangular, pointed crown ; the posterior lobe has a low, horizontal, 

 sinuous edge. 



Of the two fragments of lower jaw one has been briefly described 

 by the learned comparative anatomist I have quoted above %. It 



* * Anc. Pauna of Nebraska,' p. 96. t Owen's * Odontography,' p. 489. 



\ Owen, 'Brit. Foss. Mamm.' p. 179, figs. 4, 4«; unpublished plate N, 

 Fauna Antiq. Siv. ; fig. 6, pi. xxv. PaJ. Mem. vol. i. 



