A NEW LIVING SPECIES OF HIPPOPOTAMUS. 233 



protruded above the jaw. It is capped on each side by the mere shell of the corres- 

 ponding deciduous molar. The latter has been removed in PI. 33, fig. 2, in order to 

 show the protruding permanent tooth. 



The molars. — Of the three molar teeth the middle appears to be the largest ; but 

 the posterior one is so partially protruded as to render comparison imperfect. The 

 crown of each, before it becomes worn by attrition, presents a double cone, divided 

 into four points by a longitudinal fissure. The roots of the first two molar teeth are 

 four in number, but the last has five. 



Lower Jaw. — In the lower maxilla dentition is complete, there being no remains 

 of the deciduous teeth, and'all the teeth are perfect, excepting only in the molar fangs. 



The incisors. — These two teeth are much longer and more robust than those of the 

 upper jaw. They protrude nearly on a line with the alveolar margin, and are much 

 worn away by attrition. PI. 33, fig. 4. 



The canines differ from those of the upper jaw in being much longer, and in 

 wanting the grooved or fluted character on their posterior surface. PL 34, fig. 1. 



False molars. — The first of these is smaller than the upper one. PI. 33, fig. 6. 

 The second and third are more compressed than their fellows, and run up with 

 smooth sides to a flattened cone. PI. 33, fig. 7. The fourth false molar is a little 

 smaller than those that precede it, and, like the corresponding teeth of the upper jaw, 

 shows some resemblance to a true molar in its irregular crown and rudimentary 

 points. PI. 33, fig. 8. 



The molars. — The three true molars increase in size from first to last, and differ in 

 no material respect from the upper set. The last of them, however, which has just 

 attained its adult position, has four complete points on its crown, and a rudimentary 

 one posteriorly. It has also five corresponding fangs, but these have not yet attained 

 their full length. PL 33, fig. 9. 



Measuremenis. 



Basal length of the skull, measured from the margin of the notch between the occipital condyles Inches, 

 to the anterior end of the maxillary bones, - - - - - -12.3 



From the last named point to posterior surface of the condyles, _ _ _ - 12.8 



Basal distance between the anterior margin of the upper maxilla to the end of the os palati, - 8.4 



Distance between the posterior molars, - - - - - - -1.2 



Distance between the posterior false molars, - - - - - - -1.4? 



Distance between the canines, _...____ 2.7 



Distance between the external incisors, - - - - - - - 1.7 



Distance between the internal or central incisors, - - - - - - 1. 



Inter-zygomatic diameter, -.-.----- 12.3 



Inter-parietal diameter, _.__----- 3.5 



Distance between the orbits over the surface of the cranium, - - - - 3.9 



