LEIDY'S OSTEOLOGY OF THE HEAD OF HIPPOPOTAMUS. 209 



Upon the right side of the lower jaw, the third premolar apparently had been broken 

 out long before the eruption of the fourth, so that this, which ordinarily in Hippo- 

 potamus, in the upper and lower jaws, always appears stunted in growth, for want 

 of space, is as well developed as any of the other premolars, and better than the 

 corresponding tooth of the opposite side. 



2. The skull of an adult female. From the Cape of Good Hope. Deposited in the 

 Academy by Dr. Morton. 



Several of the sutures of the face are partially ossified, and the interraaxillaries 

 have become inseparable from the maxillaries. 



The molars are considerably worn down, and, with the exception of the last, have 

 had their enameled grinding surfaces obliterated. The first true molar has been 

 entirely deprived of its enamel. The first premolar has been shed, and the alveolus 

 obliterated. The succeeding six molars form an unbroken row. 



3. A lower jaw ^ probably of a male. From the Cape of Good Hope 1 Donor ? 

 The permanent molars are all fully protruded, and none have their enameled 



grinding surface obliterated. The first premolar has been shed, and the succeeding 

 six form an unbroken row. 



4. Head of a young male. Locality ? Presented by Dr. P. B. Goddard to the 

 Academy. 



The temporary premolars were about being shed, and the corresponding per- 

 manent teeth were protruding. The temporary true molar retains its position in 

 both jaws, but is much worn. The first permanent true molar is fully protruded, 

 and the summits of its lobes are worn into the characteristic trefoil appearance. The 

 second had not yet protruded, and the third was only partially developed. The first 

 premolar has been already lost, and the alveolus only partially remains, except on 

 one side of the lower jaw, where it is entirely filled up. The intermaxillaries are 

 detached from the specimen, and lost. 



The inferior incisors still retain part of their enamel armature, at the distal 

 extremity. 



5. An inferior mid incisor and canine. Presented by Capt. Geisinger, U. S. N. 

 The incisor is cylindrical, slightly curved, sixteen inches long, and seven inches 



in circumference. The canine measures twenty-six inches along its convexity. 



6. Two upper and two lower canines. Presented by Mr. Jacob Gilliams. 

 These are apparently from several individuals of adult size. 



Comparison of the male and female head, of Hippopotamus Capensis. — The differ- 

 ence in general size of the head, in the two sexes of Hippopotamus Capensis is not 

 much, the excess being, of course, in favor of the male. The length of the latter is 



53 



