1892.] WILK' DENTITION OF PROCAYIA CAPENSIS. 39 



of Hyrax (viz., the Rhinoceros, Tapir, and Horse), which never 

 possess more than seven cheek-teeth (molars and premolars), while 

 showing all stages in the development of the canine. He has 

 succeeded in showing that many of the earlier observers figured and 

 described these canines, mistaking them for the 1st premolars, on 

 account of the resemblance between the latter in the second dentition 

 and the milk-canines. But although the 1st premolar in the second 

 dentition is much reduced and has sometimes only one fang, it is 

 situated some distance from the premaxillo-maxillary suture, and in 

 the first dentition has a large crushing crown and is two-fauged. He 

 considers that the canines, together with the 1st premolar, are under- 

 going suppression, and that as a consequence of this the former teeth 

 have lost their more typical characters. 



With the exception of Giebel (12, 13) and Brandt (2), all observers 

 state that there is only a single pair of incisors in the upper jaw. 

 These two authorities, however, have described in the young animal 

 a second small and posterior incisor, which is early shed and is 

 situated in the premaxilla behind the large first milk-incisor. This 

 tooth is not to be confounded with the milk-incisor No. 1, which is 

 a large tooth situated between the two permanent ones, as figured by 

 Cuvier (5) and Blainville (1) ; it undoubtedly represents a 2nd upper 

 incisor, although in all probability it is only a milk-tooth, always 

 present in the foetus, but seldom, I believe, persistent after birth. 

 Giehel and Brandt were of opinion that Cuvier mistook these small 

 incisors for canines ; but as the former are situated in the gum which 

 covers the premaxilla, while the latter lie well within the maxilla, 

 their position implies that he did not understand what is generally 

 supposed to be the fundamental distinction of the canine, viz., that 

 it is typically a single-fanged pointed tooth implanted in the maxilla 

 just behind the premaxillo-maxillary suture. 



It has been already noted that no observer has seen more than 9 

 teeth in the upper jaw ; none of those who describe the presence of 

 a canine make the slightest allusion to the presence of 2 upper 

 incisors, and further perusal of the descriptions alluded to shows 

 that those who described the 2nd incisor almost certaiidy were 

 dealing with Cuvier's canine. This is probably due to the fact that 

 tiie earlier observers do not seem to have had access to some of the 

 monographs of their predecessors, but it does not excuse a modern 

 European writer like Lataste having apparently failed to consult a 

 classical work like Brandt's Monograph on Hyrax, or a standard 

 one such as Bronn's ' Thier-Reich.' 



II. Results of the present Investigation. 



The material which I have examined was kindly placed at my 

 disposal by Prof. Howes, and consisted of 5 fcetal examples of Hyrax 

 capensis preserved in spirit, being the specimens the placenta of which 

 was described by Prof. Huxley before this Socitty in 1863 \ The 



1 P.Z.S. 1863, p. 655. 



