THE DENTITION OF THE PIG. 371 



of (c) tlie third head, which is slender, arises from the 

 fibula, and sends its long and delicate tendon to the 

 dorsum of the second digit. 



The peronceus longus is present, and its tendon is inserted 

 into the entocuneiform and the second metatarsal. There 

 is no peroncBUs brevis. K peronceus Mi et 5ti digiti arises from 

 the upper part of the fibula, behind the peronceus longus, 

 and ends in a tendon which passes behind, and on the inner 

 side of, that of the latter muscle, to the dorsum of the foot, 

 where it divides into two branches which join the extensor 

 sheaths of the fourth and fifth digits. 



The extensor brevis goes to the two middle digits, and is 

 connected with the middle tendon of the extensor longus. 



The interossei are similar to those of the manus. 



Tlie foraiula of the milk dentition of the Pig (which is 

 complete at the thu'd month after birth) is d.i. — d.c. —- 

 d.m. - — • 



The outer upper incisors are directed obliquely outwards 

 and backwards. In the upper jaw, the anterior two molars 

 present sharp longitudinal edges, while the posterior two 

 have broad crowns vdth two transverse ridges. In the 

 mandilDle the anterior three molars have sharp longitudinal 

 edges, while the hindermost has a broad, three-ridged crown. 



The first permanent molar is the first tooth of the per- 

 manent set which comes into place (at about six mouths 

 after birth), and the permanent dentition is completed in the 

 third year, at which time the first deciduous molar, which 

 is not replaced, falls out. Hence the formula of the per- 



3.3 2 \ 3*3 3*3 



manent dentition is i. -— c. - — - p.m. — - m. -— = 40. 



The permanent incisors in the upper jaw have short, 

 broad, vertically-disposed crowns, and lie in a longitudinal 

 series, the external being separated by an interval from 

 the others. The elongated inferior incisors lie side by side, 

 are greatly inclined forwards and upwards, and are grooved 

 upon their upper or inner faces. The strong, angulated 



