chap, ix.] TEETH : VIVERRID^E. 227 



VIVERBIDM. 



Of the Viverridse, Herpestes and Crossarchus are the only 

 genera represented in collections in quantity sufficient to repay 

 study of their dental variations. In the teeth of these two genera, 

 however, variation is considerable and appears in some interesting 

 forms. 



In Herpestes there is first some evidence of variability in the 

 number of the incisors, including one case of extra incisor. Next 

 the facts respecting the presence or absence of the anterior pre- 

 molar are of some consequence, both as illustrating the general 

 variability and modes of Variation of this tooth, and also be- 

 cause the normal presence or normal absence of the anterior pre- 

 molar is one of the characteristics of different species, which shew 

 a progression in this respect. There is one case which should 

 probably be looked on as an example of duplicate anterior pre- 

 molar. 



There are besides two cases of duplicates of large premolars, 

 but of true supernumerary molars in series only one case was 

 seen. Another specimen shewed what is perhaps partial division 

 of a molar. Of 130 skulls, five had supernumerary teeth, not 

 including cases of unusual presence of anterior premolar. 



Incisors. 



The following cases shewed departure from the normal i|. 



)2. Herpestes gracilis : an extra incisor in lower jaw. 7^ and T 5 in 

 place and clearly recognizable on both sides, but between the two 

 second incisors are three small teeth, all of about the same size and 

 shape. Neither of these is a milk-tooth, for the milk-teeth are dis- 

 tinctly different both in size and form. There was no evidence to shew 

 which tooth was the supernumerary one. B. M., 826, a. 



)3. H. nipalensis ^ : only four incisors in lower jaws. This is a re- 

 markably clean and sound skull. The four incisors stand close together, 

 filling up the whole space between the two lower canines. There is no 

 reasonable doubt that only four lower incisors have been present. It 

 is difficult to see that any of the four incisors exactly corresponds with 

 any of the normal teeth; for while the two lateral teeth are of about 

 the same size as normal P, they have a different position, arising from 

 the outer sides of the jaw, slightly in front of the roots of the canines, 

 whereas normal 7- arises internal to the other incisors. To what extent 

 the alteration in position is correlated with the change in number 

 cannot be affirmed. B. M. 146, m. 

 ' 4 H. persicus : only four incisors in lower jaw. Judging from 

 general appearances it seemed that T l was missing from both sides. The 

 teeth stand in a close series between the canines, which are nearer 

 together than in normal specimens. The consequence of this to the 

 arrangement of the bite is curious. The left lower canine bites in its 

 normal place, between the upper canine and ^ s ; but the right lower- 

 canine bites in front of the upper &, which is displaced backwards 



15—2 



