Chap. 37 



MAMMALS AND MANKIND 



755 



Fig. 37.3. The speed of a mammal — portrait ot Citation. The thoroughbred 

 horse is developed for speed. The world's record for one mile was made by Cita- 

 tion of Calumet Farms, Lexington, Kentucky, who ran at Golden Gate Fields, 

 Albany, California in one minute and 33 and three fifths seconds, June 3, 1950. 

 For a human run the fastest mile to this date is three minutes and 58 seconds, by 

 John Landy of Australia, June, 1954. (Portrait of Citation, by Allen F. Brewer, Jr., 

 equine artist, Lexington, Ky.) 



ceives the urinogenital and digestive tubes, as it does in the amphibians, reptiles 

 and birds. Only two species have survived, the duckbill (Ornithorhynchus) — a 

 semiaquatic animal with soft fur, and the spiny anteater or Echidna with coarse 

 hair and spines that lives in dry country (Fig. 37.5). The duckbill deposits its 

 two leathery-shelled eggs in its burrow and crouches on them during incuba- 

 tion. The anteater carries her one egg in a fold of abdominal skin warmed by 

 her body until it hatches. The membranes of the embryo (amnion, chorion, 

 allantois and yolk sac) are essentially like those of reptiles. The mammary 

 glands produce the milk which the young ones lick from the skin; monotremes 

 have no nipples. 



Marsupials — Subclass 2, Marsupialia. These are mammals with a brood 

 pouch or marsupium on the outer surface of the body, as in koalas and well 

 known in the kangaroos (Figs. 37.6, 37.7). Most marsupials live in Australia, 



