38 



MR. M. F. WOODWARD ON THE [Jan. 5j 



4. On the Milk-Dentition of Procavia {Hyrax) capensis and 

 of the Rabbit {Lepus cuniculus) , with Remarks on the 

 Relation of the Milk and Permanent Dentitions of the 

 Mammalia. By M. F. Woodward, Demonstrator of 

 Zoology, Royal College of Science, London'. 



[Eeceived January 5, 1892.] 



(Plate II.) ] 



I. Historical. 



The dentition of such an interesting Mammal as Hyrax, as may 

 readily be supposed, has been carefully studied by many zoologists, 

 who, probably owing to the fact that many of them based their 

 descriptions upon one or two dried skulls only, have given the most 

 varied interpretations of the teeth. As a result we find a great 

 discrepancy in the dental formulae given in their various monographs 

 and in the text-books compiled from them. 



Most of the earlier authorities agreed as to the absence of canines, 

 but disagreed as to the total number of teeth present (viz. 34 or 

 36) and as to the number of true molars and incisors, the most 

 commonly accepted formula being i. \, c. \, pm. ^, m. 5=34. Many 

 observers, however, state that there are present at one time 8 cheek- 

 teeth above, and as they regard the extra tooth as a molar, they 

 formulate the molars as 3-4 above and 3 below. More rarely we find 

 the incisors described as being \ ; and lastly, two observers '■' have 

 described a pair of canines as being present in the upper jaw. 



All are agreed as to the number of teeth present in the lower jaw 

 of the adult, viz. 9 ; but there is much disagreement as to the total 

 number of teeth present in the upper jaw (viz. 8-9), and also as to 

 the homologies of the individual teeth and sets of teeth. 



Most state emphatically that there are no canines present in either 

 jaw. Cuvier, however, asserted (4) that there was a pair of small 

 canines present in the upper jaw of the young animal, and he re- 

 garded them as the accessory teeth of Pallas (25), but this opinion 

 he afterwards retracted (5). 



It remained for Lataste (19) to be the first to show definitely 

 that there is present in the upper jaw of all young specimens a pair 

 of small canines ; he has shown that these are shed early in life 

 and that they rarely persist til! the completion of the second den- 

 tition. He bases his conclusions on the shape and position of these 

 teeth together with the characters of the 2nd maxillary tooth 

 (1st premolar) as exemplified in a very large series of skulls of all 

 ages, and finally on a comparison with the teeth of the near allies 



^ Communicated by Prof. Howes. 

 ^ Cuvier (4) and Lataste (19). 



