SAGHATHERIUM ANTIQUUM. 87 



is the larger ; they seem to be the protocone and tritocone of Scott's nomenclature. 

 The most peculiar feature of these teeth is, that from the postero-external cusp a ridge 

 runs along the posterior border of the tooth, and when worn gives rise to a surface 

 continuous with the ectoloph. It seems probable that this posterior ridge belongs to 

 the cingulum, and may include elements equivalent to the metastyle and hypostyle ; it 

 does not seem to be comparable to the metaloph of the molars. The antero-internal 

 cusp is large and V-shaped, the anterior arm of the V running forwards and outwards 

 towards the parastyle, while the posterior arm extends outwards and backwards to the 

 postero-external cusp, and seems to include a distinct element. It is probably from 

 the increase in size of the latter, and of a minute cusp here situated immediately behind 

 the inner end of the antero-internal cusp, that the metaloph of the molariform premolar 

 of the later forms has arisen. At the same time it should be observed that in 

 Megalohyrax the premolars are much more nearly similar in plan to the molars than 

 in Saghathermm, and the change there required to convert the posterior premolar into 

 a tooth similar to the anterior molar would be a slight one. The minute postero- 

 internal cusp above referred to can be seen in the second, third, and fourth premolars, 

 but is largest in the last. The anterior premolar differs somewhat from the others. 

 Its outer wall, as in them, consists of three elements, viz. a large parastyle forming the 

 anterior angle of the tooth, and behind this a protocone and tritocone. From the last- 

 named a ridge, apparently composed of two cusps {}. metastyle and hypostyle), forms 

 the posterior border of the tooth. The antero-internal angle of the tooth is occupied 

 by a large cusp (deuterocone) borne on a separate root. In the type specimen, in 

 front of the anterior premolar are the broken roots of the canines (c.) ; the larger 

 posterior root is oval in section, the anterior nearly circular. The series of cheek- 

 teeth, as a whole, forms a curved line. The two last premolars are wider from within 

 outwards than from before backwards ; the second is nearly square. 



No specimen of the mandible in which the teeth of the symphysial region are 

 preserved is known ; but in one in which the symphysis is present the roots or 

 the alveoli of these teeth can be seen, and from these it appears that there were 

 probably three pairs of procumbent incisors, of which i: 1 and i. 2 were larger 

 than ^. 3. All form a closed series and were not separated by any interval from those 

 of the opposite side. The canine was a one-rooted tooth separated by a very short 

 diastema from the anterior premolars. The two anterior premolars are each borne by 

 two transversely oval roots ; the third and fourth by three roots, of which two are 

 anterior, while the third or posterior one is transversely elongated. In no specimen is 

 the crown of the first premolar preserved. The other premolars each consist of a 

 pair of V-shaped columns, the anterior arms of the V's being much the longer ; 

 the posterior arms are placed almost transversely across the crown. At the anterior 

 end of the anterior V there is a small tubercle which projects backwards and partly 

 closes the opening of the V. This seems to be the parastylid of Osborn's 



