﻿72 PLEISTOCENE MAMMALIA. 



the lion ; in the tiger, both anterior and posterior transverse measurements of the crown 

 are nearly equal. The highly divaricate character of the fangs of the smaller teeth 

 appears to be more characteristic of the recent lion than the more parallel arrangement 

 of the larger, which we have found more prevalent in the jaguar. PM 2 of the hyaena 

 somewhat resembles this tooth. It is, however, much shorter and broader, the cone (a) 

 is lower, the cusp (b) is generally obsolete, the cusp (c) is much larger, and the cingulum 

 more developed. 



Premolar 4. (Pis. I, VI, XII, figs. 10, II, 12). — This tooth is built precisely on 

 the same plan as PM 3 with the exception that the cingulum is developed into a generally 

 well-marked, posterior cusp (e), which, however, is occasionally obsolete, as in fig. 12. 

 The primary cone (a) is also much higher and more trenchant, and (b) and (c) are much 

 larger and more distinct. The cingulum is strongly marked, and developed, as in PM 3, 

 into a cutting edge posteriorly and internally. The section of the crown is oval ; the 

 posterior and anterior transverse measurements being nearly equal. The fangs are stout 

 and long, cylindrical, slightly divaricate, and narrowed at the tips. 



True molar 1. Pis. I, VI, XII, figs. 13, 14, 15. — The lower true molar consists of 

 two trenchant blades ; the cutting edges are inclined to each other at an angle, 

 slightly obtuse on the lateral, and very open internally on the vertical aspect ; 

 externally the surface is convex, fitting the sectorial portion of the upper p remolar 4 . 

 Internally the surface is excavated in such a fashion that the trenchant edges are always 

 preserved as the tooth is worn by PM 4 as in fig. 13. The width of the excavation at 

 the base of the cleft is one of the distinctions between this tooth and that of the hyaena. 

 The posterior blade (a) is somewhat higher than the anterior (b) ; the former is traversed 

 throughout by a trenchant edge, which leads posteriorly to the almost obsolete cusp (c), 

 and anteriorly it is divided from the cusp (b) by a deep cleft. The trenchant edge of (5) 

 is continued only on its posterior upper border, the cusp being rounded anteriorly. The 

 cingulum is well developed, and on the inner surface there are three well-marked 

 central tubercles, besides others which are variable in number and size. The cusp (<5), 

 and half the cone (a), are supported by a large anterior fang, a compressed oval in 

 section, slightly recurved and trapezoidal in outline ; the remainder of (a), with the little 

 cusp (c), are supported by a posterior fang), small, short, straight, cylindrical, and 

 slightly tapering. 



We have already indicated the only difference we can perceive between lion and tiger 

 in the dentition of the lower jaw, in our description of PM3. The variations, however, 

 in this respect, in the corresponding teeth of the recent Felida, prove that it is a mere 

 tendency and not a specific character. 



The only fossil teeth of Felis we know of that can be compared with those of Felis 

 spelaa are those of Felis aphanista of Dr. Kaup, from the Miocene of Darmstadt, and 

 the Felis arvernensis of MM. Croizet and Jobert. The teeth of the former animal, 

 among which may be reckoned the upper premolar 4, ascribed by Dr. Kaup to 



