917 



Notation for the Teeth in the Class Mammalia." By Richard 

 Owen, Esq., F.R.S. &c. 



The author commences by a brief statement of the facts and con- 

 clusions recorded in a paper by Sir Ev. Home on the dentition of 

 the Sus JEthiopicus, in the Philosophical Transactions for 1799, 

 p. 256 ; and gives the results of an examination of the original 

 specimens described and figured by Home, and of other specimens 

 showing earlier stages of dentition, which lead to the following 

 conclusions as to the number, kinds, and mode of succession of 

 the teeth in the genus Phacochcerus, The tooth answering to the 

 first milk-molar and first premolar in the upper jaw, and those 

 answering to the first and second milk-molars and corresponding 

 premolars in the lower jaw of the common Hog are not developed. 

 Eight successive phases of development of the grinding teeth of the 

 African Wart-hogs are described and expressed by the following 



notation : — 







Phase. 

 1. 



No. of grinding 

 teeth. 



5-5 • 

 viz. 



4-4- 



Kinds of teetli. 



j a 2, « 3, a 4, m i, m 2. 

 \d2>^ 4, m 1 , m 2. 



n. 



6-6 . 



fp2,pS,p4;,?nl, m 2, tn 3. 

 IP 3, p 4, ni 1 , m 2, tn 3. 



IIL 



5-5 . 



VIZ. 



4-4 



f p 3, p 4, m 1, m % m 3. 

 \p 4, m 1, m 2, m 3. 



IV. 



4-4 . 



VIZ. 



4-4 



p 4, m 1, m 2, m 3. 



V. 



4-4 . 



VIZ. < 



\p 3, p 4, m 2, m 3. 

 \p 4, m 2, m 3. 



VI. 



3-3 . 



VIZ. 



3-3 



p 4, m % m 3. 



VII. 



2-2 . 



VIZ. 



2-2 



p 4, m 3. 



VIII. 



1=1 viz. 



1-1 



m3. 



These observations prove that, contrary to the opinion of Home 

 and Cuvier, the Wart-hogs have deciduous teeth, succeeded verti- 

 cally by premolar teeth; in the Phacoch(Erus jEliam^ at least, 

 three deciduous teeth are, in some individuals, succeeded by as 

 many premolar teeth ; and, as a general rule, two deciduous teeth 

 are displaced vertically by two premolars. The first true molar is 

 remarkable for its unusually early development, which is followed 

 by an unusually early abrasion and expulsion, when its place is ob- 

 literated by the second true molar being pushed forwards into con- 

 tact with the last premolar. This tooth is as remarkable for its 

 longevity, and remains after the wearing away and shedding of the 

 second true molar, when the last true molar advances into contact 



