390 MAMMALIA 



ridae, all elongated, chisel-like, growing from persistent pulps; 

 premolars few. Placenta deciduate and disc-shaped. Cecum 

 large. (Figure 219.) 



Rodents vary in size from the porcupine of three feet in length 

 to the small mouse about three inches long. Squirrels {Sciuridae) 

 are found everywhere except in Australia and Madagascar. Four 

 species are found in the United States and Canada. 



The Calijornia ground squirrel {Citellus beecheyi) (see Figure 

 220) lives in and on the ground, storing its food of fruits, nuts, and 

 grain in the ear in its underground burrows. It is of particular 

 interest since it carries bubonic plague caught from rats. 



Other squirrels include the Eastern Gray squirrel which lives in 

 the tree tops and the 7'ock squirrels or " chipmunks " which live in 

 fences and among the roots of large trees. The largest squirrel in 

 the world is the great Malabar squirrel of India, which grows to be 

 eighteen inches long, with a tail fourteen and one-half inches long. 



The Easter?i chipjnunk (Tamias st?-iatus) ranges from Illinois 

 eastward. It is a lively little creature about ten inches long, and 

 seems fond of nests in rocky crevices and decayed tree trunks. It 

 usually has several entrances to its tunnel. It feeds on acorns, 

 nuts, and grains but is also a consumer of mice, birds' eggs and 

 insects. Its chief enemy is the weasel but it is also preyed upon by 

 birds. 



The flying squirrels {Sciuropterus) are not able to fly, but by 

 means of a furry membrane spread from the anterior to the posterior 

 limbs they plane from one tree or branch to another. The Asiatic 

 flying squirrel reaches a length of eighteen inches. 



The p}'airie-dogs (Cynomys) live in villages on the plains. They 

 are a great pest in the cattle country. Rattlesnakes visit their 

 burrows in search of young " dogs " and burrowing owls are fre- 

 quently found in vacated burrows, but the " happy family " does 

 not exist. 



The woodchuck, or "groundhog," lives on clover and other grasses 

 and may enter isolated gardens. He lives in a burrow and hiber- 

 nates in November. It is traditional that he wakens on " ground- 

 hog day," February 2, and " if he sees his shadow, sleeps six weeks 

 longer, which means a cold spring," 



The gray marmot is found in the Northwestern part of North 

 America and is called the " whistler " on account of its danger signal. 



