No. 3.] OSTEOLOGY OF MESOHIPPUS AND LEPTOMERYX. 349 



rises much higher above the level of the teeth and projects more 

 directly vertically and less posteriorly. The horizontal ramus 

 is slender and shallow, with a nearly straight inferior border. 

 The symphysis is quite long and differs from that of Tragulus 

 in being much less sharply compressed inferiorly, and in having 

 its superior margins erect, not flaring and everted. 



The foramina of the skull of Leptomeryx are, on the whole, 

 most like those of the tragulines, but not without some im- 

 portant differences. The optic foramina are confluent and 

 situated far forward ; the foramen lacerum anterius is rela- 

 tively small ; the foramen rotundum has not coalesced with the 

 foramen lacerum anterius, as it has in Tragulus, but is situated 

 close to the foramen ovale. Owing to the small size of the 

 auditory bulla, the foramina in this region are very different 

 from those of the chevrotains, the foramina lacerum medius 

 and posterius being large, and the carotid canal not grooving 

 the side of the bulla. Post-glenoid, stylo-mastoid, and condylar 

 foramina are present. At least one large venous foramen 

 pierces the parietal near the sagittal crest. The infra-orbital 

 foramen is placed very low down, just above/. 2. The foramina 

 in the anterior part of the orbit are very characteristic in the 

 tragulines, and are thus described by Riitimeyer : "Von einer 

 Fossa sphenomaxillaris, wie sie sonst den Wiederkauern zu- 

 kommt, ist eigentlich bei Tragulina nicht zu reden, da der 

 Alveolartheil des Oberkiefers so niedrig ist, dass er nur als 

 Boden der Augenhohle dient, ohne dieselbe zu verengen. Nur 

 der trichterformige Eingang des Infraorbitalcanals bleibt als 

 Rest einer Fossa sphenomaxillaris iibrig, wahrend das Foramen 

 sphenopalatinum, und zwar von rundlicher Form, vollkommen 

 frei an der Innenwand der Augenhohle liegt. Unter ihm fiihrt 

 das For. palatinum superius nach abwarts, um sich in das 

 aufallend weite und ungefahr in der Mitte der Gaumenbeine 

 liegende Gaumenloch zu offnen " (No. 45, p. 19). This de- 

 scription applies almost exactly to Leptomeryx, except that 

 the opening of the infra-orbital canal is divided into two parts, 

 as it shows a tendency to be in Tragulus ; the lachrymal 

 foramen is placed much higher up than in that genus, and the 

 supra-orbital canal has the same position and relative size, but 

 the groove which runs forward from it is shorter and less 

 distinctly marked. 



