256 PROCEEDINGS OF THE GEOLOGICAL SOCIETY. [Mar. 11, 



summit of which has been worn by an upper tooth ; the chief cone 

 is worn only along its anterior slope, as in the canine. 



The second premolar, p 2, shows a marked increase of size, and 

 chiefly of antero-posterior extent, which is 5^ hues (O^'Oll), the 

 height of the crown being 3 lines (O'^'OOZ). The hind basal lobe is 

 well-marked : any trace of a front basal lobe has been worn off by 

 the abrasion along the anterior slope of the main cone, which shows 

 a linear tract of dentine : both the anterior and posterior depressions 

 of the inner surface are well-marked. The second premolar of the 

 Dlchobune leporina * differs from that of the present species in its 

 well-marked anterior lobe. In both species this tooth is supported 

 by two fangs. 



The third premolar, p 3, of the Dichobune ovina is chiefly distin- 

 guished from the second by an increase of thickness and an indica- 

 tion of an anterior lobe : the crown of this tooth is abraded along its 

 anterior slope and at the summit of the hind lobe. 



In the fourth premolar, p4, -d second cone is developed on the 

 inner side of the chief cone ; this has also an anterior and posterior 

 accessory tubercle, the anterior of which has a basal ridge. The 

 summits of both principal cones and of both accessory cones are 

 abraded in this tooth : its antero-posterior extent is less than that of 

 the third or second premolar ; but its transverse thickness is greater. 



The first, m 1, and second, m 2, true molars consist each of two 

 transverse pairs of cones ; a third pair, the inner cone of which is 

 minute, is added to the back of the third molar, m 3. 



In the first molar, m 1, the two outer cones are worn down to near 

 the base of the inner cones, which have only their summits touched. 

 The outer cones have an almost equilateral triangular section with 

 the outer angle rounded off and the inner side or base slightly con- 

 cave. The inner cones are m.ore compressed, with their outer side 

 more convex than the inner one, which shows a feeble narrow de- 

 pression near the anterior and posterior border, and a rudiment of 

 an accessory lobule at the back part of the base of the anterior cone ; 

 fig. 3, ml. 



The second molar, m 2, resembles the first, but is rather larger ; 

 the summits of its outer cones are more worn than those of the sub- 

 lanceolate inner cones. 



The chief part of the third molar, m 3, closely resembles the second 

 molar : its accessory division plainly consists of a pair of cones ; the 

 inner one being rudimentary, the outer one of the same antero-poste- 

 rior extent as the normal outer cone, but lower and thinner, and 

 oblique in its position. 



The unequal wear of the true molars gives their grinding surface 

 an aspect turned a little outwards ; that of the premolars and canines 

 shows that those compressed, conical, antero-posteriorly extended 

 teeth are interlocked with similarly-shaped teeth of the upper jaw. 



From the Dichobune cervina (which M. Gervais thinks, and I con- 

 cur with him, may belong to the genus Dichodon f ) described and 



* Ossemens Fossiles, ed. 1836, pi. 90. fig. 2. 



\ *• L'examen que nous avons fait de cette piece dans les collections de la So- 



