Vol. 70.] YERTEBEATES EE05I BEITISH EAST AFEICA. 165- 



the ascending ramus, the surface of which behind this ridge is much 

 roughened for the attachment of muscles. The lower part of this 

 ridge forms the hinder border of the alveolar surface : that surface 

 extends some distance behind the last molar, and is perforated at its 

 posterior angle by a small foramen. The outer face of the ascending 

 ramus is nearly flat ; unfortunately, both the coronoid process and the 

 condyle are wanting. This mandibular ramus is similar to that of 

 Dinotheriwm cuvieri, which, however, is rather larger and stouter, 

 the outer face of the ramus being more convex. 



The teeth preserved in this specimen are pm 4 -m 3 . The premolar 

 and the last two molars have already been described in detail in the 

 account 1 of the type jaw ; the only differences in the present speci- 

 men, apart from its rather smaller size, are that the anterior lobe 

 of the premolar is smaller and the talon of m 3 more rounded and 

 its inner edge crenulated ; there is also a more distinct trace of a 

 cingulum on its hinder face. 



The first molar (PI. XXVIII, fig. 1), as usual in the genus, con- 

 sists of three transverse ridges, the posterior one being much the 

 smallest. There is a slight trace of a cingulum at the outer end of 

 the anterior valley, and also on the posterior face of the third ridge ; 

 on the inner side the cingulum is absent. In Dinotlierium cuvieri 

 the cingulum is better developed at the outer end of the anterior 

 valley, and it is also present on the outer side of the first ridge. 



The dimensions (in centimetres) of this specimen are :— 



Length in a straight line (so far as preserved) 38*8 



Depth of ramus beneath m., 10*5 



Length of molar -premolar series (pm. r m 3 ) 24 ■ 3 



The dimensions of the teeth (in centimetres) are : — 

 pm± 



m„. 



mgth. 



Width 



4-6 



4-0 



5-6 



4-0 



5-8 



5-2 



6-5 



5-3 



A right upper premolar (PL XXVIII, fig. 2) in the collection is 

 nearly quadrate in outline, the width being a little greater than 

 the length. The crown is composed of two transverse crests, which 

 are highest at their outer and inner ends, being more obviously 

 formed by the union of an outer and an inner cusp than is the 

 case in the lower molars. The two outer cusps show some tendency 

 to unite one with the other, the outer end of the transverse valley 

 being much shallower than the inner, so that in an advanced state 

 of wear the surfaces of the two cusps would become continuous. 

 The cingulum is well developed on both the anterior and the posterior 

 faces of the tooth ; it is also present at the inner end of the trans- 

 verse valley and as faint irregular tubercles on the outer face. 

 There were three roots to this tooth, one at the antero-external 

 angle, a second occupying the anterior portion of the inner side ; 



1 Proc. Zool. Soc. 1911, p. 943. 



