ON THE EONES OF THE HIPPOPOTAMUS. 399 



arches, longer in proportion: tlie junction of the os malse to the 

 muzzle is there effected by an oblique line and not by a sudden slope ; 

 from whence it results that the contracted portion of the muzzle is 

 shorter in proportion. Besides the differences resulting to the profile 

 from those just enumerated, we may moreover remaik that the occiput 

 rises more suddenly, so that the fall of the sagittal crest, towards the 

 interval of the orbits, is more rapid, and consequently the vertical height 

 of the occiput is greater. 



The fossil head represented in the plate is one of those splendid 

 specimens that enrich the Museum of the Grand Duke at Florence. 



In the I ova er jaw (plate 35, figs. 3 and 4) I find the interval of the 

 two branches much narrower, and the angle formed by their internal 

 surfaces less rounded in front. The slant towards the posterior in- 

 ferior angle returns less rapidly towards the front, and the inferior 

 edge also rises a little less in front, and consequently forms at that 

 spot a less concave edge, which causes it to make a decided angle with 

 the anterior edge below the canine, which does not exist in the living 

 hippopotamus. 



The lower fossil jaw, w T hich is in a very good state of preservation, 

 is also in the Museum of the Grand Duke at Florence. 



I have deposited one somewhat less complete in the King's Museum. 

 Its dimensions are as follow : — 



Distance from the anterior to the posterior angle . „ 0,456 



From one anterior angle to the other 0,335 



From one posterior angle to the other 0,443 



Length of the space occupied by the jaw teeth , 0,307 



Distance between the first anterior grinders 0,095 



Distance between the last grinders 0,057 



Breadth of the rising branch 0, 1 55 



Breadth of the coronoid apophysis 0,1 18 



Height of the jaw, from the posterior angle to the articulating 



coronoid apophysis 0,336 



Length of the symphysis 0,186 



2. The Vertebra. 



Of these I have had five, not one of which is precisely similar to 

 the corresponding one in the living hippopotamus. 



A fossil cervical of an hippopotamus, which appears to have been 

 the fifth, with a body broader and higher by one-fourth, is not longer, 

 and its annular part is One-third narrower : but its articular and 

 transverse apophyses appear to have been pretty much the same. 



A fourth or fifth dorsal (plate 36, fig. 12) is strongly distinguished 

 by the base of its spinal apophyses being much broader and more 

 bluuted in front. 



A thirteenth dorsal has its articulating surfaces more elongated, and 

 one spinal apophysis directed further towards the back ; a first lumbar 

 vertehrse (plate 36, fig. 13) is only distinguished by a spinal apophysis 

 smaller and straighter than the corresponding one in the living animal; 

 a first sacrum (plate 36, fig. 14) has its body less depressed, and 

 the anterior articulating apophysis larger and closer to the body of the 

 bone. 



