xxv] 



RODENTIA 



703 



forms a parachute-like membrane which supports it in its great 

 leaps from tree to tree. In these manoeuvres it is assisted by the 

 broad flattened tail. The Flying Squirrel is common in the temperate 

 part of the United States. A similar but larger species (S. sabrinus) 

 may be seen at dusk leaping from tree to tree on the Mountain of 

 Montreal. Anomalurus, found in West and Central Africa, is also 

 called a Flying Squirrel, since the skin of its sides is prolonged into 

 a parachute-like membrane (Fig. 354). It differs from Sciuropterus 

 however, in having a round tail provided with horny scales under- 

 neath, which assist in climbing, and in having its "parachute" 



FIG. 354. The African Flying Squirrel, Anomalurus fulgens. 



supported by a cartilaginous rod arising from the elbow. In reality 

 Anomalurus is a surviving member of a primitive group of Rodentia 

 termed PROTROGOMORPHA, intermediate in character between Squirrels 

 and Mice, most of which are extinct. 



The Mice and Rats, MURIDAB, have naked tails with scales under- 

 neath. The ordinary Rat is the brown Norway Rat, Mus decumanus, 

 which was introduced some time ago into England and had almost 

 everywhere driven out the old English Black Rat, M. rattus. Of 



