CORYPHODON. 607 



they, therefore, retain the structure of the second and third premolars 

 in the Tapir, with slight modifications which make a nearer 

 approach to the structure of the molars of the Rhinoceros. The 

 first and second are implanted by three, roots \ the rest by four, the 

 two inner ones being connate for some extent. 



In the lower jaw the first premolar is relatively smaller and 

 simpler than in the Tapir : the crown supports a subcompressed 

 conical obtuse cusp, with a small anterior and larger posterior talon, 

 and is girt by a basal ridge : in the second the anterior and especially 

 the posterior basal lobes increase in size : in the third the posterior 

 lobe almost equals the principal eminence, and is connected to it by 

 a longitudinal ridge crossing the intervening valley : there is a basal 

 ridge on each side the posterior lobe : in the three true molars of the 

 lower jaw the crown is broader, quadrate, and supports tw^o transverse 

 anteriorly-curved eminences, with an anterior and posterior basal 

 ridge, and they very closely resemble those of the Tapir : but the last 

 molar differs by the development of the posterior talon into a wedge- 

 shaped eminence half the height of the two that precede it. (PL 135, 

 fig. 8.) 



223. Coryphodon.{\) — This extinct Pachyderm, which was as 

 large as a Horse, and of equal antiquity with the true Lophiodons, 

 differed from them in having the second and third eminences of the 

 last lower molar (PL 135, fig. 9) blended together into an obtuse- 

 angled ridge, with each angle developed into a point ; the anterior 

 eminence is straight and is higher than the posterior one ; it has each 

 extremity prolonged into a point. 



From the outer extremity of each of the two principal transverse 

 eminences a ridge is continued obliquely forwards, inwards and 

 downwards : the anterior one extends to the inner and anterior 

 angle of the base of the crown : the posterior one terminates at 

 the middle of the interspace between the two ridges. From the 

 back part of the posterior transverse eminence a ridge, or talon, 

 extends downwards and outwards. 



Thus the crown of the last molar of the present species has 

 the two transverse eminence^ of a Lophiodon's molar so modified 



(1) History of British Fossil Mammalia, 8vo. p. 299. 



