170 ON THE EXTINCT MAMMALIA OF 



exhibit, in the same manner, series of prominent, narrow, buttress-like ridges, and 

 from the base of the postero-internal lobe anteriorly there springs a strong tubercle. 

 This is variable in the degree of its development in different individuals, but generally 

 is proportionately better developed than in the Deer. See figure 5, plate XIV. 



The last upper premolar has a bi-lobed crown, with the lobes like those of the true 

 molars, but proportionately longer, as usual in all the upper premolars of most living 

 ruminants. The inner lobe exhibits a slight disposition to the formation of a process, 

 projecting into the interspace of the lobes, as in the Deer. 



The anterior two upper premolars have a crown which is a modification in form of 

 that of the last premolar. The outer lobe appears like that of the latter extended in 

 breadth, while the inner lobe is proportionately reduced to a median cone connected 

 by basal ridges with the sides of the outer lobe. The first premolar differs from the 

 second only in being less well-developed. 



The inferior true molars, figure 6, resemble those of the Musks more than those of 

 the Deer, from the circumstance that the lateral buttress-like ridges internally of the 

 inner lobes are less prominent than in the latter, and the median ridge is more 

 obtuse. 



The last of the series of lower molars has the usual accessory lobe of this tooth in 

 ruminants divided into a distinct pair, less well-developed than those in advance, and 

 the inner one less well-developed than the outer one. 



The last inferior premolar, figure 6, has a broad crown, narrowing anteriorly and 

 rising in a prominent median point. Internally it is trilobate, or exhibits three 

 conoidal prominences separated by a pair of vertical gutters. At the back part of the 

 crown a narrow pit extends deeply from the triturating surface. 



The second lower premolar, figures 7, 8, is a reduced form of the last one ; and the 

 first premolar is still less well-developed, and is without the posterior pit of the 

 crown. 



The worn triturating surface of the lower premolars presents an elongated tract of 

 dentine, trilobate internally, and bilobate posteriorly except in the first one. 



The last lower temporary molar has three pairs of lobes to the crown, as usual 

 among ruminants. 



The last upper temporary pi'emolar has a broad crown, composed of three lobes 

 externally and a single lobe postero-internally, connected with the fore part of the 

 tooth by a long basal ridge. 



The other temporary premolars above and below appear to resemble the anterior 

 premolars of the permanent series in a less well-developed condition. 



Measurements taken from three specimens of Leptomeryx Evansi are as follow : 



