GROUP OF THE HADGKRS. 



213 



grinding suriace. In Lyncodon this tubercled 

 tooth is wanting. 



The premolars present the greatest amount 

 of variety. The last of these, the carnassial 

 of the upper jaw, usually furnished with two 

 strong external cusps and an internal heel, 

 gets blunted like the lower carnassial, and in 

 the sea-otter in particular it does so to such a 

 degree that it may wholly lose its character. 



In a large number ot genera, the badgers, 

 gluttons, and true martens, there are three 

 other premolars in front of the upper carnas- 

 sial, brinaino- the total number of these teeth 

 up to tour. These three premolars increase 

 in size from before backwards, and either 

 have a laterally-compressed sharp-pointed 

 cusp or are in the form of a more or less trun- 

 cated cone. In some genera, as, for example, 

 in the otters, the first premolar is so small 

 and insignificant that it is placed, not behind, 

 but on the inner side of the canine. In the 

 lower jaw there are originallv tour pre- 

 molars in front of the permanent carnassial, 

 and these have similar forms to those in the 

 upper jaw, and exhibit the same increase in 

 size from before backwards. 



But this original number ot tour premolars 

 above and below is preserved only in the 

 true martens and the gluttons, and in both 

 jaws there is observed in difterent members 

 of the group a gradual diminution in the 

 number of these teeth from before backwards, 

 a diminution whose last stage is seen in the 

 Lyncodon, in which the number is reduced 

 to two in each half of the jaw. The two 

 extremes in this series are thus as shown in 

 the followino- formulas: — 



Complete Dentition. 



Reptcep Dentition. 

 1 ■ 2 ■ I 



Mustela, = zS. Lyncodon, '^' = jS. 



' 3 • I • 4 ■ 2 -^ - 3 • I ■ ; ■ I 



All the Steps intermediate between these 

 extremes occur. 



Leaving out of account the incisors and 

 canines, the number of which is always the 

 same, namelv 16 (except in the single instance 



aboxe mentioned), we find in fact the follow- 

 ing variations in the premolars and molars 

 proper: — 



4 ' I 



-^-^ = 3S teeth: Mustela, Gulo. 



4 - 



4_:_i ^ ^ ^^^^j^^ j Meles, Taxidea, Helictis, 

 3 ■ - i Lutra, Arctonyx. 



^ . J i Mydaus, Mephitis (inpart), 



"tt^ = 34 teeth : | Galictis, Putorius, Rhab- 

 "^ " ( dogale. 



2 • I 



7^^ = 32 teeth: ]\lephitis (in part). 



2 ■ 1 

 2 ■ I 



^•,2 teeth: ^lellivora. 



28 teeth: Lvncodon. 



Beyond doubt this progTessi\e reduction 

 distinguishes a family, the characters of 

 which are not yet completely determined, and 

 which along with archaic types possesses a 

 number ot other torms. 



The Mustelida mav be divided according 

 to the structure ot their teet into three groups: 

 Plantigrada: the Badgers (Melida); Digiti- 

 grada: the Martens (Martida): \\'eb-footed 

 forms: the Otters (Lutrida). 



GROUP OF THE BADGERS 



(AUiLIDAl. 



Plantigrade carnnores, with tliic]<-set clumsy body, 

 short feet, and highly de\"eloped anal glands. 



Our Common Badger {J/c/cs fa.nis), fig. 

 loS, mav be taken as type ot the group. 



The rather long head gradually narrows 

 in front to a naked snout, like that of a pig, 

 with which the badger has often been com- 

 pared also on account of the thick rounded 

 bodv somewhat higher behind than Ln front. 

 The eves and ears are small ; the legs very 

 short and thick, the paws naked on the sole 

 and with five toes carrying long curved claws, 

 which on the fore-paws are \-ery prominent 

 and, as in all burrowing animals, sharp and 

 broad. The tail is short and thickly covered 

 with hair. At its root near the anus is a 



