in the Collection of the British Museum. 271 
I. Without any cheek-pouches. Fur soft, consisting of fusiform 
hairs and a soft under-fur. ars ovate. Arboreal. Tree- 
Squirrels. | 
A. The limbs free, without any parachute. 
1. The front edge of the cutting-teeth broad, rounded, closely longi- 
tudinally grooved. 
1. Rueirurosciurvs. Lars large, long, pencilled; head 
large, short ; tail broad, clavate. 
u1. The front edge of the cutting-teeth narrow, compressed, smooth. 
2. Scrurus. Lars ovate, pencilled or tufted externally ; nose 
rounded ; tail longer than the body. 
3. Macroxus. Ears ovate, covered with short adpressed 
hairs; nose short, blunt; cheek-pouch none; tail longer than 
the body. 
4, Ruinoscrurvs. Ears ovate, covered with short adpressed 
hairs; nose acute, produced; cheek-pouch none; tail longer 
than the body. 
B. The limbs enclosed in skin, forming a parachute; tail short, 
broad, pennate ; front edge of cutting-teeth smooth. 
5. Scruroprervs. Lars ovate, covered with short adpressed 
hairs. Europe, Asia, and America. 
Il. Without any cheek-pouches. Fur short, rigid, with flat chan- 
nelled spines, without any under-fur. Ears rounded, scarcely 
raised. ‘Terrestrial. Ground-Squirrels. 
6. Xervus. Ears narrow, short, mostly raised above the head ; 
face short, blunt ; cheek-pouches none; fur short, rigid. Africa. 
Ill. With distinct cheek-pouches. Fur soft, consisting of fusiform 
hairs and a soft under-fur. Ears ovate. Fossorial. Bur- 
rowing Squirrels. 
7. Tamias. Ears ovate, covered with short adpressed hairs ; 
face short, rounded; cheek-pouches distinct. Hurope, North 
_ Asia, and America. 
I. Without any cheek-pouches. Fur soft, consisting of fusiform 
hairs and a soft under-fur. Ears ovate. Arboreal. Tree- 
Squirrels. 
A. The limbs free, without any parachute. 
1. The front edge of the cutting-teeth broad, rounded, closely longi- 
tudinally grooved. 
1. RHEITHROSCIURUS, nov. gen. 
Head large, compressed, short; ears large, with a pencil of 
elongated hairs at the tip; cutting-teeth broad, rounded in front 
