COXDYLARTHRA. 439 



posterior external tubercle is reduced in size, and the posterior cingulum is 

 wide and tuberculate. It rises into a large posterior internal tubercle. The 

 external cingulum and tubercle are weak. The enamel is slightly obsoletely 

 wrinkled except where worn. 



There is no precanine diastema in the lower jaw. The middle incisors 

 project almost horizontally forwards, and the alveoli ai'e oval in outline. 

 The crown of the canine is a little recurved. It is rather short, and of 

 triangular section. The sides are a little convex, and the anterior angle not 

 acute. No ridges or grooves. First premolar one-rooted, separated by a 

 short space from the canine, and separated by a longer space, equal to its 

 own long diameter, from the second premolar. Crown lost. , The crown 

 of the second premolar is triangular, and is in profile an equilateral triangle, 

 with the base longer than the sides. There is no heel, but the crown is 

 widerbehind and has a vertical fossa on the inner side of the middle line. The 

 inner edge of this fossa terminates above in a rudiment of an internal cusp. 

 Similarly there is in the unworn tooth a rudiment of an anterior cusp on the 

 superior pai't of the anterior edge ; probably not a constant character. No 

 cingula. The third premolar has a form like the second, but it is larger and 

 is wider behind. The posterior face has two grooves, the internal the 

 shorter, and terminated above by a well-marked internal cusp The ex- 

 ternal posterior bounding ridge is somewhat tubercular. No heel nor 

 cingulum; a rudiment of anterior basal cusp. The fourth premolar tooth 

 is a larger tooth than the third, and is as long as the first true molar. There 

 is a large, but low anterior basal tubercle, and the internal anterior cusp 

 is larger than the external, and a little posterior to it. The oidy posterior 

 cusp, the external, is the size of the anterior basal tubercle. Internal edge 

 of heel not elevated ; no posterior median tubercle. • 



In the true inferior molars, the internal anterior tubercle is a little 

 larger than the external. The anterior basal ledge is distinct, but there is 

 no other cingulum. The only median tubercle is j^osterior, and is well 

 developed, though smaller than the others. A low ridge connects the pos- 

 terior or external tubercle with the base of the anterior inner. The last 

 true molar is a little smaller than the second, and is more naiTOwed behind 

 than they. The posterior median tubercle is as large as the posterior 



