22 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 6l 



two female skins varying- more in color from each other than they do 

 from the male skins. Number 164635, male, is light smoke-grey in 

 color and is the lighter skin. It is quite similar in color to the col- 

 ored figure of the white rhinoceros in Andrew Smith's Illustrations of 

 the Zoology of South Africa, 1849. The skin of the other male, 

 number 164589, is also light smoke gray of Ridgway. Number 164592 

 is the darker female, the color being light broccoli-brown. Appar- 

 ently the young soon attain the same shade of color as the adults, for 

 the calf, number 164588, has already attained adult coloration, and is 

 actually somewhat darker than the lighter male. 



The only parts of the body which show a growth of hair are the 

 terminal margins of the ears and the apical one-fourth of the tail. 

 The hair of the ears is quite soft and is an inch or so in length. The 

 hair covering of the tail is stiff and bristly, and confined to a streak 

 along both edges of the flattened tip. In the two male skins the hair 

 covering these parts is glossy black and quite profuse, but in the 

 female skins the covering is much thinner and decidedly brownish in 

 color. The young at birth are no more hairy than the adults, possess- 

 ing only the ear and tail fringes of coarse hair. 



SKULL CHARACTERS 



The bones of the skull exhibit a really wide range of variation due 

 to age and sex. The individual variation is much less in the series 

 which is too small to exhibit much of this character. In the series of 

 twelve skulls only four show any wear on the last molars which would 

 justify their consideration as old adults. The last molars do not 

 become functional until the animal has reached middle life. All of the 

 milk molars are in use in two of the skulls, though worn down to 

 very short crowns. Four others are practically of the same age as 

 regards the condition of the last molar which is just erupting through 

 the bone. The next two have this tooth in place, but no wear has 

 yet taken place. The oldest of the series are the four skulls with the 

 last molar showing wear. The series thus gives us four stages based 

 on the condition of the teeth ; the first, showing a full set of milk 

 molars ; the next, with the four milk molars still in use ; and the last 

 molar just breaking through the gums ; the third stage, in which the 

 last molar has moved up in place; and, the final one, in which the 

 whole permanent series show wear. 



In referring these various ages to the three classes usually used 

 for fully grown animals, a certain amount of confusion is unavoidable. 

 All those individuals showing any trace of milk dentition have been 



