TEETH. 



9i3 



The dentition of the Weasel tribe (Muste- 

 lidfe) is illustrated (mfig. 580, IV.) by that of 

 the Otter, Mustela Lutra of Linnaeus, and 



which is essentially a great aquatic Weasel or 



o 2 j j 



Polecat; its dental formula is i. - , c. - , 



33' 

 4 4 1 ] 



P- o Q> m " 5 -K ' = 3G - In the Martin cats 



o o .c " 



(Mustela martes, L.), the little homotype of 

 p. 1 above is present in the lower jaw ; in the 

 bloodthirsty stoats and weasels, p. 1 is absent in 

 both jaws ; as it is likewise in the great sea- 

 otter (E>t/fi/dra), in which also the two middle 

 incisors are wanting in the lower jaw. In this 

 animal the second premolar (p. 3) has a strong 

 obtuse conical crown, double the size of that 

 of p. 2 ; the third premolar (p. 4) is more than 

 twice the size of p. 3, and represents the 

 upper carnassial or sectorial strangely modi- 

 fied; the two lobes of the blade being hemi- 

 spheric tubercles. The last tooth, m, 1, has 

 a larger crown than the sectorial, and is of a 

 similar broad crushing form. In the lower 

 jaw the molar series are not separated bv any 

 interspace: the first and second premolars 

 have oblique obtuse conical crowns. The 

 third premolar (p. 4) is more than twice the 

 size of the second (p. 3) and supports a large 

 anterior hemispheric protuberance with a 

 small internal tubercle and a posterior basal 

 ridge. The first true molar has an oblong 

 quadrate crown with an anterior small tubercle, 

 a larger and more prominent inner one, and 

 the rest of the broad horizontal surface un- 

 dulating. The second true molar has a trans- 

 versely elliptical crown depressed in the 

 centre. When the teeth are in apposition, 

 the anterior third of the first true molar below 

 is applied to the inner tubercle of the last 

 premolar above ; the rest of its crown plays 

 upon that of its homotype, the first true molar 

 in the upper jaw, leaving a small part of that 

 tooth to receive the appulse of the second 

 true molar below, which has no corresponding 

 tooth in the upper jaw. 



The MustelidcB present great constancy in 

 regard to the number of their true molar 

 teeth; with one exception, the Ratel (Mclli- 

 vura), in which m. 2 is absent below, they 

 have one true molar on each side of the 

 upper jaw, and two on each side of the lower 

 jaw ; the second of these has always a broad 

 tubercular crown, like the one above. The 

 upper true molar is supported by one inner, 

 and sometimes by one (Pittorius, Gulo), 

 sometimes two (Mustela, Lutra, Melphltis), 

 outer fangs. The second true molar below 

 is also tubercular, but has a single fang. The 

 crown of the first true molar below offers 

 many gradations from the sectorial type, as 

 manifested in Putorius and Gu/o, to the tuber- 

 cular type, as in the Taira, Ratel, and sea- 

 otter. The principal varieties occur, as 

 usual, in the comparatively less important 

 premolars : in the Martins and Gluttons, 

 they are as numerous as in the dog ; the 

 first, in both jaws, being implanted by a single 

 fang ; the rest by two, with the exception of 



VOL. IV. 



the last above, which has three roots. In 

 the otter, we find the first premolar removed 

 from the lower jaw ; and the second (now 

 the first) shows its true homology by its 

 double implantation, as well as by the position 

 of its crown behind the first in the upper 

 jaw (p. 1). In the Stoats, Skunks, and 

 Ratels, the premolar series is further reduced 

 by the loss of the anterior tooth (p. 1) in 

 both jaws, and by the diminution of the size of 

 p. 2, which thus becomes the first in both jaws, 

 and which is also now implanted by a single 

 fang. In a South American Skunk, the second 

 premolar disappears in the upper jaw, leaving 

 there only the homologues of the third and 

 fourth of the typical formula, p. 4 being 

 always the sectorial in the Mustelidce, as in 

 other terrestrial Carnivora. This tooth, 

 under all its modifications, retains the blade 

 with the lobe, corresponding to the middle 

 one in the feline sectoral, generally well 

 developed and sharp-pointed ; the differences 

 are principally manifested by the proportions 

 of the inner tubercle, and the relative size of 

 the third root supporting it. But the upper 

 sectorial, being a premolar, and therefore 

 requiring less modification of the crown to 

 adapt it for its special functions, manifests a, 

 more limited extent of variety than the lower 

 sectorial, which, being a true molar, requires 

 greater modification of the typical form of its 

 crown to fit it for playing upon the sectorial 

 blade of p. 4 above. 



Melidee. In this sub-.family \ comprise 

 the European Badger (Meles), the Indian 

 Badger (Arctonyx)., and the American Badger 

 (Taxidca) ; which, with respect to their den-, 

 tition, stand at the opposite extreme of the 

 Mustelidie to that occupied by the predaeeous 

 Weasel, and manifest the most tuberculate 

 and omnivorous character of the teeth. The 

 33 1 1 33 



, . . 



formula is:-*. 



c. 





] ; p. 



: = 30 



The canines are strongly developed, well 

 pointed, with a posterior trenchant edge ; 

 they are more compressed in Arctonyx than 

 in Mclcs. The first lower premolar (p. 1) 

 is very small, single-fanged, and, generally, 

 soon lost. The first above, corresponding 

 with the second in the dog, is also small, and 

 implanted by two connate fangs. The second 

 upper premolar (p. 3) has a larger, but 

 simple, sub-compressed conical crown, and is 

 implanted by two fangs: the third (p. 4) re- 

 peats the form of the second on a larger scale, 

 with a better developed posterior talon, and 

 with the addition of a tri-tuberculate low flat 

 lobe, which is supported by a third fang : the 

 outer pointed and more produced part of this 

 tooth represents the blade of the sectorial 

 tooth and the entire crown of the antecedent 

 premolars. The true molar in Melcs (/. ]) 

 is of enormous size compared with that of 

 any of the preceding Carnivora : it has three 

 external tubercles, and an extensive horizontal 

 surlare traversed longitudinally by a low 



3N 



