914 



TEETH. 



ridge, and bounded by an internal belt, the 

 cingulum of Illiger: this tooth has a similarly 

 shaped, but relatively smaller, crown in Arc- 

 tonyx* The second premolar below (p. 2) 

 is commonly the first, through the early loss 

 of the minute one in front ; its fangs are 

 usually connate, as in its homotype above. 

 The third and fourth premolars slightly in- 

 crease in size, have simple compressed conical 

 crowns, and two fangs each. The first true 

 molar below (m. 1) now retains little of its 

 sectorial character, the blade being represented 

 only by the two anterior small, compressed 

 pointed lobes; behind these, the crown ex- 

 pands into an oval grinding surface, narrower 

 in Arctonyx than in Meles, supporting three 

 tubercles and a posterior tuberculate ridge: 

 it has generally two principal roots and a 

 small intermediate accessory fang, as in the 

 otter. The second molar (m. 2), which ter- 

 minates the series below, is of small size, and 

 has a rounded flat crown, depressed in the 

 centre, and with two small external tubercles; 

 its two short fangs are connate. In the 

 Labrador Badger, the last premolar has a 

 larger relative size, the part corresponding 

 with the blade of the sectorial, is sharper 

 and more produced, and the internal tu- 

 bercle has two lobes; the succeeding molar 

 tooth is reduced in size, and its crown pre- 

 sents a triangular form. The first true molar 

 below has its sectorial lobes better developed : 

 these differences give the North American 

 badgers a more carnivorous character than is 

 manifested by the Indian or European species. 

 Sub-UrsidcE. In other allied genera, which, 

 like the badgers, have been grouped, on ac- 

 count of the plantigrade structure of their 

 feet, with the bears, a progressive approxi- 

 mation is made to the type of the dentition of 

 the Ursine species. The first true molar 

 below soon loses all its sectorial modification, 

 and acquires its true tubercular character : 

 and the last premolar above becomes more 

 directly and completely opposed to its homo- 

 type in the lower jaw. The Racoon ( Procyon f) 

 and the Coati (Nasua) present good examples 

 of these transitional modifications ; they have 

 the complete number of premolar teeth, the 



, . . . 33 1 1 44 

 dental formula being, i. ^ -, c. ., p. . _ ., 



2 2 



m. ^ o : = 40. The development of the in- 

 ner part of the crown of the last upper pre- 

 molar, which constitutes the tubercle of the 

 sectorial tooth, now produces two tubercles on 

 a level with the outer ones which represent the 

 blade; and the opposite premolar below (p. 4), 

 which is the true homotype of the modified 

 sectorial above, begins to acquire a marked 

 increase of breadth and accessory basal tu- 

 bercles. All the lower premolars, as well as 

 the true molars, have two fangs; the three first 

 premolars above have two fangs, the fourth 

 has three, like the two true molars above. 

 The dental formula of the Indian Bentu- 



* See Odontography, pi. 128, Jfy. 13, m. 1. 

 f Ib. pi. 129,^0. 7. % Ib.jigs. 813. 



rong (Arctictis) and Kinkajou (Cercoleptes) is 



. 3 _3 i_l 33 22 



' 3=3' C ' 1=1' P- 5=3' m ' 2=2 '' = 36 ' 



PhocidcB. We have seen a tendency to 

 deviate from the ferine number of the incisors 

 in the most aquatic and piscivorous of the 

 Musteline quadrupeds, viz. the sea-otter 

 (Enhydra), in which species the two middle 

 incisors of the lower jaw are not developed in 

 the permanent dentition. In the family of 

 true seals, the incisive formula is further re- 

 duced, in some species even to zero in the 



3 3 



lower jaw, and it never exceeds ^p All 



the Phocld<e possess powerful canines ; only in 

 the aberrant walrus ( Ttichechui) are they absent 

 in the lower jaw, but this is compensated by the 

 singular excess of development which they 

 manifest in the upper jaw. In the pinmgrade, 

 as in the plantigrade, family of Carnivores we 

 find the teeth which correspond to true mo- 

 lars more numerous than in the digitigrade 

 species, and even occasionally rising to the 

 typical number, three on each side ; but this, 

 in the seals, is manifested in the upper and 

 not, as in the bears, in the lower jaw. The 

 entire molar series usually includes five, 

 rarely six teeth on each s'de of the upper 

 jaw, and five on each side of the lower jaw, 

 with crowns, which vary little in size or form 

 in the same individual ; they are supported in 

 some genera, as the Eared Seals (Otarite) 

 and Elephant Seals (Cystopkora*\ by a single 

 fang ; in other genera f by two fangs, which 

 are usually connate in the first or second 

 teeth ; the fang or fangs of both incisors, 

 canines and molars, are always remarkable 

 for their thickness, which commonly sur- 

 passes the longest diameter of the crown. 

 The crowns are most commonly compressed, 

 conical, more or less pointed, with the " cin- 

 gulum " and the anterior and posterior basal 

 tubercles more or less developed; in a few of 

 the largest species they are simple and ob- 

 tuse, and particularly so in the walrus, in 

 which the molar teeth are reduced to a 

 smaller number than in the true seals.J In 

 these the line of demarcation between the 

 true and false molars is very indefinitely in- 

 dicated by characters of form or position ; 

 but, according to the instances in which a 

 deciduous dentition has been observed, the 

 first three permanent molars in both jaws 

 succeed and displace the same number of 

 milk molars, and are consequently premolars ; 

 occasionally, in the seals with two-rooted 

 molars, the more simple character of the 

 premolar teeth is manifested by their fangs 

 being connate, and in the Stenorhynchus serri- 

 dens the more complex character of the true 

 molars is manifested in the crown. There is 

 no special modification of the crown of any 

 tooth by which it can merit the name of a 



* Odontography, pi. 132,^. 7. 



t Ib.fgs. l-y4. 



j The relation of Trichechus to the PJiocidte is 

 analogous to that of Machairodus to the Felidce, and 

 also, in the simplification of the molars, to that of 

 Proteles to Canidte. 



