Dr. C. I. Forsyth Major — Fliohyraxfrom Samos. 551 



wall (Fig. 4), and at an early stage of wear (Fig. 5) they become 

 fused with the inner part of cusps 4 and 5 respectively, while the 

 intermediate conules, the outer cusps of the crests, tend respectively 

 towards cusps 1 and 2 of the outer wall (Fig. 4) and become 

 ultimately, in their turn, fused with them (Figs. 5 and 3). 



When comparing our figures of the Hyrax teeth with the diagram 

 of a Mmoceros- tooth ^ it becomes apparent that in the latter each 

 crest unites with the outer wall in one place only, and this fusion is 

 as a rule brought about by those parts of the crests which correspond 

 to the intermediate conules.* 



The upper cheek teeth of Hyraces exhibit besides an anterior and 

 a posterior basal cingulum, and, less frequently, an outer one also. 

 All these secondary parts, including the last one, are represented in 

 the molars of Pliohyrax (Fig. 2). The main differences between 

 the fossil and the recent teeth, apart from the complication of the 

 fossil m. 3, are the following : (1) The fossil teeth are more buno- 

 dont ; for, as far as their worn condition permits us to judge, the 

 inner cusps remained independent for a longer time than in recent 

 Hyraces (compare Fig. 2 with Fig. 3). (2) In the fossil teeth the 

 outer cusps (1 and 2), especially the latter, Osborn's mesostyle, are 

 more prominent than in Hyraces. Both these characters point 

 towards a more primitive condition of the fossil teeth. 



Measurements. 



mm. 



Length of the three true molars in the middle line 94 



Breadth of skull from sagittal suture to outer margin of orbit (the greatest 



breadth of the skull would therefore be approximately 210 mm.) ... 105 

 Breadth of skull between posterior external margins of the infraorbital 



foramina ... ... ... ... ... ... ... ... ... 90'S 



Breadth of palate between anterior parts of m. 1 45 



Maximum of vertical height of orbit 43 



Long axis of same ... ... ... ... ... ... ... ... 46 



Height of zygoma below orbit ... ... ... ... ... ... 48 



From posterior upper margins of infraorbital foramen to anterior margin 



of orbit 69 



The addition to our knowledge of the genus ' Leptodon,' due to the 

 skull in the British Museum, does not bring us nearer to the 

 Hyracidse than the mandible described by Gaudry ; for, besides some 

 dilferences pointed out in the molars, the recent Hyraces differ in 

 their skull from the fossil — (1) by comparatively larger orbits, 

 situated at a lower level, and not so far backward as in the latter ; 

 (2) by the anterior border of the orbits being situated either above 

 the anterior margin of the posterior premolar (p. 1), or, in the 

 species with smaller cheek teeth, even above the anterior part of 

 p. 2 ; (3) by the more anterior position of the infraorbital foramina ; 



1 Osborn, op. cit., p. 87, fig. 5. 



^ It seems probable that what is called 'crochet' in the Jihiiwceros-tooth. is the 

 homologue of the posterior intermediate cusp (metaconule) ; therefore, in those teeth 

 in which the crochet is present as such, the inner cusp of the posterior lobe (hypo- 

 cone) would appear to join directly the outer wall. 



