Fra. 171.—Three species of jack-rabbits, differing in size, color, and markings, but 
believed to be derived from «1 common stock. The differences have arisen 
through isolation and adaptation, The upper figure shows the head and fore legs 
of the black jack-rabbit (Lepus insularis), of Espiritu Santo Island, Gulf of 
California ; the lower right-hand figure, the Arizona jack-rabbit (Lepus alleni), 
specimen from Fort Lowell, Arizona ; and the lower left-hand figure is the San 
Pedro Martir jack-rabbit (Lepus martirensis), from San Pedro Martir, Baja 
California. 7 
