Ecureuil), properly the name of the wellknown red, bushy-tailed British arboreal mammal, Sciurus vulgaris, typifying the genus Sciurus and the family Sciuridae, but in a wider sense embracing all the rodents included in this and a few nearly allied genera.
For the characteristics of the family Sciuridae and the different squirrel-like genera by which it is represented, see Rodentia.
Beavers are nearly allied to the squirrels (Sciuridae), agreeing in certain structural peculiarities of the lower jaw and skull.
In the Sciuridae the two main bones (tibia and fibula) of the lower half of the leg are quite separate, the tail is round and hairy, and the habits are arboreal and terrestrial.
The uterus may be double, each division opening by a separate os uteri into a common vagina, as in Leporsdae, Sciuridae, and Hydrochoerus, or two-horned, as in most species.