PHEXACODUS. 467 



and posterior, but no external nor internal cingula. The anterior cingulum 

 rises into an angle at the antero-exterior corner of the crown, which is not 

 very prominent. 



Of the true molars the first and second are about equal and the third 

 is considerably smaller. The external face of the second is more oblique 

 posteriorly than that of the first. The third is an oval with the narrower 

 end external. The external cusps are subequal and subround in section in 

 the first and second molars, and the internal cusps are also subequal and 

 subround. The intermediate tubercles are present except on the posterior 

 half of the second molar, where it is wanting, agreeably to the more con- 

 tracted space at that point. Both these teeth have cingula all round the 

 crown excepting on the internal side. The external cingular tubercle is 

 obtuse. In the third true molar the two posterior tubercles are much 

 reduced in size, and there is no intermediate tubercle between them. There 

 is one between the anterior paii-, which are of usual proportions to the 

 crown. The anterior and exterior cingula are the only ob\aous ones on 

 this tooth. 



The inferior incisors are directed very obliquely forwards, and have 

 the crowns compressed and wider than the roots. The crown of the third 

 is not certainly known. The crown of the inferior canine is directed 

 straight upwards, is about the size of that of the upper jaw, and has a 

 subround section at the base. The molar series is continued from it with- 

 out diastema. The first premolar is a good deal smaller than the second, 

 has one root, and a crown higher than long with its base rising forwards 

 and its apex acute. The second premolar has a simple compressed conic 

 crown with apex above the anterior root. The third has a similar form 

 viewed externally, but is larger, and has a posterior face, which in its pres- 

 ent worn state is a plane narrow triangle, with the base downwards. It is 

 probable that in the unworn state of this tooth the internal tubercle was 

 rudimental or wanting, and the heel very short. The fourth premolar has 

 a large heel, and well developed internal and anterior tubercles. The ridges 

 connecting the external posterior tubercle and the external median with the 

 internal median and anterior, respectively, form two V's like the inferior 



