232 CLASS MAMMALIA. 



surface ; but when they have attained three years, they 

 contain about twenty-two complete rings. In more ad- 

 vanced age they thicken, at the base a succession of half 

 annuli or wrinkles are seen, and they are sometimes two 

 feet long ; the spiral turns are then perfect, so that after 

 death, if the osseous core within be dry, they can be screwed 

 on and off with ease. The colours of the hair vary likewise 

 with age : while young they are of a pale fulvous, more or 

 less ochery, with white about the mouth, inside of the ears, 

 breast, belly, inside of the limbs, buttocks, anterior part 

 of the thighs, interior and posterior part of the upper arms, 

 and the rest of the legs ; a white streak passes also about 

 midway of the fulvous along the flanks ; there is sometimes 

 a dark streak in the form of a crescent passing round the 

 anterior part of the eyes next the forehead ; when older, 

 the white increases on the nose, forms a circle round the 

 orbits, extends on the lower jaw and throat, and the legs 

 often become entirely white, excepting the tufts on the 

 knees, which are always brown ; the tail, about five inches 

 long, is likewise white beneath, brown or fulvous above, 

 and without a tuft at the end. But the fulvous colours 

 darken gradually, the forehead, back of the ears, top of the 

 neck, superior part of the tail, and the middle and lower 

 part of the thigh, to beneath the joint, alone remain fulvous ; 

 the chaffron, cheeks, throat, sides of the neck, shoulders, 

 back, croup, and flanks, deepening into a sepia-brown, and 

 the streak on the middle of the flanks becomes intense black, 

 with a second of the same colour some inches lower on the 

 edge of the white colour of the belly. It is at this period 

 that the colouring is complete, and the term spotted is ap- 

 plied ; they are then of a growth and maturity to claim a 

 herd of females, but there are individuals, and they are 

 the most vigorous, which become nearly all shining black 

 and white, the fulvous being wholly obliterated ; these 

 have the horns wrinkled and solid as before noticed, and 



