MAMMALIA 389 



The African and Oriental jackals are scavengers, but also rob 

 hen-roosts. They feed on figs and fruits as well. 



There are over 200 breeds of domestic dogs. They are derived 

 from at least seven wild species, including the jackals of Asia, the 

 jackal-wolf of Northeast Africa, the gray wolf and the coyote of North 

 America. 



Sub-Order Pinnipedia. {Seals and Walruses.) — The Pinnipedia 

 are aquatic carnivores with their digits united by a membrane. 

 The Northern fur seal iOtaria ursina) is not a true seal, but is a sea 

 bear or sea lion, found on the Pribilof Islands. It spends about 

 two-thirds of each year far out at sea, making a circuit of six thou- 

 sand miles in the open ocean without touching land. The United 

 States protects a large fur seal herd on the Pribilof Islands, Alaska. 

 The California sea lion {Otariidae) feeds mostly on squids and octopi, 

 but fishermen consider it injurious as a fish consumer. The true 

 seals {Phocidae) have no external ears and their nostrils are dorsally 

 situated. Among the common forms are the harbor seal and the 

 hair seal. The bluish gray fur of the harp seal is extremely valuable. 

 The hooded seal males have a nasal sac that can be inflated to a 

 length of ten inches. Elephant seals (twenty feet long) are nearly 

 extinct, but a few were discovered recently at Guadaloupe Island. 

 Walruses {Odobenidae) are clumsy on land, but have extremely 

 powerful tusks (canine teeth) and can wreck small boats. They 

 eat shellfish, crustaceans and aquatic plants. Formerly supplying 

 the Alaskan natives with fuel, light, harness and boats, the demand 

 for walrus oil has led to their almost complete extermination. 



Fossil Relatives of the Carnivora. — Primitive Creodonta are 

 found in the Eocene of North America, Europe, and Africa, and are 

 almost indistinguishable from the Insectivora and Ungulata of that 

 period. Fossil dogs appeared in the Eocene of North America. 

 Fossil cats are known from the Oligocene period where the huge 

 saber-tooth tigers lived from the Miocene to the Pleistocene. Bears 

 came in with the Miocene, and the great cave-bear ( Ursus speleus) 

 of Europe was hunted for food during the Pleistocene period. Seals 

 and walruses have descended from primitive Pinnipedia of the 

 Miocene period. 



Order VI. Rodentia. — Vegetable-feeding, mostly of small 

 size, with furry integument, clawed digits, and usually plantigrade 

 limbs. Clavicle usually present. No canines, never more than two 

 incisors in lower jaw and but two in the upper except in the Lepo- 



