212 



LEIDY'S OSTEOLOGY OF THE HEAD OF HIPPOPOTAMUS. 



other about a half inch wide, placed to the inside of the posterior groove. In Hippo- 

 potamus amphibius, old and young, the enamel forms a continuous investment of 

 every part excepting the anterior third of the circumference of the tooth. 



The anterior abraded surface of the upper canine, in the male Hippopotamus 

 amphibius, has its long diameter nearly perpendicular, and the inner plane of the 

 surface is not more than one-tenth of the whole. 



The enamel is thicker on the canine of the young, than upon that of the old head 

 of this species. 



The incisors above and below are smaller than in the male H. Capensis. 



In the male H. amphibius the upper mid incisors, which are nearly three inches 

 in circumference, have the enamel band relatively broad, being eleven lines. 



In the young specimen, supposed to be of the female, the mid incisor is a little 

 over three inches in circumference, and is four and a half inches long, and has two 

 distinct bands of enamel, one antero-external eight lines wide, the other postero- 

 internal and five lines wide. The lateral incisor is about three and three-quarter inches 

 long, by two and a half in diameter, and possesses an antero-external band of enamel 

 two and a half lines Avide. 



Comparative Table of Measurements of the Head of Hippopotamus Capensis, and H. ampliihiiis. 



Length from occipital condyles to anterior extremity of intermaxillaries 

 Length from the notch of the inion superiorly to end of nasal bones 

 Length from anterior margin of orbit to anterior extremity of intermaxillaries 

 Length of hard palate -.-.-..-- 

 Greatest breadth, at posterior part of zygomae .... 



" " anterior '•' " 



Breadth of forehead, between supra-orbital margins ... 



Depth of transverse concavity of forehead, . - . . - 



Length of nasal bones ......... 



Breadth " " posteriorly 



" " " anteriorly ....... 



" at infra-orbitar foramina ...-.-. 



" canine alveoli ........ 



Semi-circumference of face, on line with infra-orbitar foramina, from 

 alveolar margin to middle nasal suture .... 



Greatest breadth of inion ........ 



Heighth of inion from occipital foramen ..... 



" of face on a line with infra-orbitar foramina ... 



Vertical diameter of orbit 



Transverse " " ........ 



Length of lower jaw from most posterior part to canine alveoli - 

 Distance from angle to edge of canine alveoli anteriorly - . - 

 Expanse of lower jaw posteriorly ....... 



Distance from angle to angle ....... 



Breadth at base below third premolars 



" canine alveoli ........ 



" between coronoid processes - - - 



jy. Capevsis. 



H. amphibius. 



Male. 



Female. 



Male? 



YouDg 



Inches, 



Inches. 



Inches. 



Female 



27 



26 



22i 



22J 



23 



22 



19 



18 



17 



151 



14 



13^ 



181 



16i 



15 



14 j 



171 



\bk 



15 



15 



11 



18 



9 J 



11 



10^ 



lOi 



10 



9 



2 



1 



1 



4 



16i 



15 



13 



11 



41 



bh 







4 



11 



24 



— 



U 



H 



5 



3.7 



4* 



13 



lU 



11.; 



lOj 



8 



11 



6i 



H 



111 



lOj 



101 



lOi 



64^ 



51 



5 



bk 



H 



6J 



H. 



6 



3 



3 



n 



3 



9i 



24 



2 



2^ 



Two specimens. 









21 20 



— 



19 



18 



15 \%h 



— 



13^ 



13 



20 191 



— 



17 



15 



161 16^ 



— 



151 



13 



9^ 11 



— 



8 



— 



15 15^ 



— 



12 



11* 



(2 



61 



