THE OSTEOLOGY OF ELOTHERIUM. -^'-'. 



elongation of the whole muzzle ; its facial portion is low, gradually diminishing in heighl 

 forward, where its suture with the premaxillary forms a very gentle, sweeping curve. 

 The longest suture of the maxillary is that with the nasal, the connection with the frontal 

 being very short, owing to the extension of the lachrymal. Posteriorly, this bone pro- 

 jects but little beneath the orbit, which has an imperfectly developed floor, and the pro- 

 jection which it sends out to the jugal is much less massive than in Hippopotamus. The 

 face gradually narrows forward, until it reaches the infraorbital foramen, expanding 

 again in front of the foramen and swelling out into the prominent canine alveolus. The 

 palatine processes of the maxillaries are long and narrow, and as the molar-premolar 

 series of the two sides form almost straight and parallel lines, the bony palate is of nearly 

 uniform width, slightly concave transversely, but almost plane antero-posteriorly. In 

 front, these palatine processes are deeply emarginated by the large incisive foramina, and 

 in the median line are still further notched to receive the long premaxillary spines. 



The palatines make up but very little of the bony palate, forming only a narrow 

 strip in front of the posterior nares, and narrow bands along the sides. The palatal 

 notches are small and shallow. The pterygoids are elongate, but quite low ; there are no 

 hamular processes or pterygoid fossae ; the two bones meet suturally along the median 

 dorsal line, completely concealing the presphenoid from view. The posterior nares are 

 long, narrow and low, extending forward to the middle of m ^ ; the opening gradually 

 contracts posteriorly, where it becomes very narrow, while the side-walls slope upward 

 and die away upon the alisphenoids. Anteriorly the nares are divided by the very large 

 vomer, which is distinctly visible, and which at its hinder termination expands into a 

 tx - ansverse plate, articulating with the palatines. The meeting of the two pterygoids 

 forms a small canal, which appears to overlie the whole length of the posterior nares and 

 to open forward into the nasal chamber on each side of the vomer. This is a very excep- 

 tional arrangement, and I am unable to suggest what its functional meaning may be 

 (see PI. XVIII, Fig. 1, c). 



The cranial foramina are, in some respects, quite peculiar. The condylar foramen is 

 large and conspicuous, being placed well in front of the condyle ; it is, however, smaller 

 than in the specimen of E. magnum which Kowalevsky has figured. The close aj)proxi- 

 mation of the paroccipital and stylomastoid processes, and the outward extension of the 

 tympanic between them, have given a somewhat unusual position to the postglenoid and 

 stylomastoid foramina ; they are crowded close together at the postero-external angle of 

 the auditory bulla, and both of them perforate the enlarged tympanic bone. The fora- 

 men lacerum posterius forms a long, narrow and curved slit at the postero-internal angle 

 of the bulla, while the foramen lacerum medium and the opening of the eustachian canal 

 occupy their ordinary position at the front end of the bulla. No distinct carotid canal is 

 visible externally. 



