COMPENDIUM OF GENERIC DISTINCTIONS. 
Genus. —Hélamys. 
1—1 1-1 33 
E 17 e = ae 33 
‘and broad. Molars with crown, divided into two portions 
by a fold of enamel. 
Head.—Ears long. 
Limbs. —Fore-feet with five toes, sharp, long claws; hinder 
with four toes, much elongated. 
Habitat.—South Africa. 
Teeth. 20, Incisors smooth 
Genus.—Dipus. 
= : 1—1 2—2 
I. abe Toy’ M. 9 
grooved, all aaa and sharp. Molars with roots. 
Head.—Ears short. 
Limbs.—Fore-feet with five toes, hind-feet with three. 
Tail.—Long, covered with hair set in double row, 
Habitat.—Part of Europe and Egypt. 
Teeth. 16. 
Sub-family.—M youina. 
Teeth.—Incisors smooth and compressed. Molars a 4 
with roots, and with transverse bands on the crown. 
Genus.—Myoxus. 
Head.—Ears moderate, rounded, and covered with short, 
fine hair. Whisker hairs, long. 
Limbs.—Fore-feet with four toes, and a wart for thumb, 
without claw. Hind-feet with five toes. 
Tail—Long, and thickly haired. 
Habitat.—Europe. 
Sub-family.—Sciurina. 
Teeth.—Incisors smooth, brown or orange-coloured in 
front. Molars complex. 
Limbs.—Fore-feet with four toes, and clawed wart for 
thumb. 
Genus.—Sciurdpterus. 
1— Si eS 
Teeth.—I. 
Ie 33 
bercles. 
Tail.—Rather short and flat. 
Development of skin along sides so as to form 
membrane. 
Habitat.—India, North America, and Siberia. 
a flying 
Genus.—Sciurus. 
Skin.—Not expanded along the sides. 
Head.—Cheek-pouches none. 
Habitat.—Europe, Asia, Africa, and America. 
Genus.—Timias, 
Head. —Cheek-pouches. 
Feet.—Shorter than those of the true squirrels. 
Tail.—Shorter than the body. 
Habitat.—North America. 
22. Molars with tu- | 
Upper incisors 
uy 
te) 
= 
Genus.—Arctomys. 
Teeth.—1I. 1-1 Py Ld 44 
1; =a 3—3 
Molars with tubercles set transversely on the 
22. 
Incisors smooth 
and rounded. 
crown. 
Head.— Cheek-pouches none. 
Limbs.—Fore-feet with four toes, 
thumb ; hind-feet with five toes. 
Tail.—Short, covered with long hair. 
Habitat.—Northern Europe and America. 
and nailed wart for 
Genus.—Sperméphilus. 
Head.—Cheek-pouches. 
Tail.—Moderate. soural form more slender than Arc- 
tomys. 
Habitat.—Northern ere and America. 
Fumily.—ASPALACIDE. 
Teeth.—Incisors very long, and visible outside the mouth. 
4-4 3-3 
Molars —— or -—— 
PAY 33 
Head.—Ears none, or very small. 
Limbs.—Front, five toes, cloven. 
General form, thick, heavy, and clumsy. 
Genus.—Spalax, 
Teeth. — 
Head.—Very flat; a abrupt at muzzle. 
under the skin. Ears, none externally. 
Limbs.—Feet short, with small claws. 
Tail.—None. 
Habitat.—Europe. 
= = complex, and small. 
Eyes hidden 
Genus.—Bathyergus. 
= : 1—1 3—3 
I. tbs = M. a5 
with deep groove, a stripe of enamel across the crown. 
Head.—Eyes very small. Ears none externally. 
Limbs.—Large digging claws on fore-feet, the claw of 
second toe the largest. 
Habitat.—Cape of Good Hope. 
Teeth. 20. 
Upper incisors 
Genus.—Saceéphorus, 
Teeth.—Incisors with deep longitudinal groove—Molars 
+4 : 
rose rootless. 
Head.—Ears very small, and rounded. Eyes very small. 
Very large cheek-pouches, nearly retractile when empty. 
Limbs. Three middle claws of fore-feet long, the. third 
the longest. 
Tail.—None. 
Habitat. —Canada. 
N.B. Diplostoma may be separated from Saccophorus by 
| the smooth incisor teeth. 
Genus.—Rhizomys. 
Teeth.—Incisors broad, smooth, and red in front; 
3—3 
molars P= : 
Head.—Broad, short, and abruptly terminated in front. 
Ears very small. Eyes also small. 
Limbs.—Fore-feet four-toed, with clawed wart for thumb. 
Habitat.—Malacca and China. 
