SKULL AND TEETH OF TAXIDEA AMERICANA. 273 



gled triaugie of nearly equal base aud perpeudicalar, the right 

 augle being aiitero-iuterual, the longest side posteroexternal. 

 When entirely unworn, it shows six or eight irregularly dis- 

 posed tubercles, all small, the general surface being quite flat, 

 aud there being no notable division, by sulcus or otherwise, 

 into different portions, such as the crown of this tooth presents 

 in most Mustelida'. The lowest part of the tooth is a small cir- 

 cular area posteriorly. This tooth roots by a long fang exte- 

 riorly, but is otherwise simply set in an irregular shallow 

 depression. The last premolar is likewise approximately an 

 equilateral right-angled triangle ; but in this case the right 

 angle is antero-exterior, the hypothenuse postero-interior. It is 

 well divided into an outer and inner moiety. The former is 

 produced into a large main cusp, with prominent heel on its 

 front base, and a smaller posterior cusp. The low inner moiety 

 shows two perfectly distinct conical cusps; one anterior, the 

 larger, with a cingulum around its base, and a smaller posterior 

 elevation directly from the border of the tooth. The middle 

 premolar is a simple conical cusp with a slight heel posteriorly; 

 it is two-rooted. The front premolar is like the last named, 

 but still smaller. I have never seen, in the adult dentition, 

 the small first premolar which is said to occur '^ in young ani- 

 mals", nor do I observe any trace of such tooth in a young 

 specimen which was just shedding ^Yhen killed. In this one, 

 the first aud last permanent premolars have just displaced the 

 earlier ones, but the middle milk-premolar is still present, with 

 the future one visible below it, about to i)ush it away. The 

 presence of four upper premolars can, therefore, only charac- 

 terize the milk dentition.* 



The upper canines offer no special points. Of the incisors, 

 the outer is very much larger than the rest; indeed, it is hardly 

 more exceeded by the lower canine than the latter is by the 

 upper canine, and its superficial resemblance to a canine is 

 striking. The other incisors are of the same size, regular, with 

 dilated trilobate ends. 



The back lower molar, as elsewhere in the family, is small, 

 circular, with a border a little higher before and behind than 

 at the sides. It abuts against the depressed back part of the 



* The small anterior upper premolar is the most variable tooth in MusteUdcv. 

 It persists in the Liitra, Enhjdris, Gulo, Mnstela, and usually for a time in 

 Conepatus; it is absent in the adult dentition of Taxidea, Mephitis, SpilogalCj 

 Putorius. 



18 m 



