EHIZOMTS BADITJS. 215 



islands, E. sinicus, Gray, from China, is figured in Hardwicke's Illustra- 

 tions. 



There are many genera of true rats found in the new world, and a few in 

 Africa. From the old continent there are several peculiar forms, some of 

 which deserve particular mention. Among these are the hamsters, genus 

 Cricetus. They have the teeth of Murines, but their tail is short and 

 hairy, and they have cheek-pouches. They belong to the Palsearctic 

 region. 



The Beaver, Castor fiber, L., is one of the most remarkable Muridts, 

 and is, by some, placed in a distinct sub-family. It has four molars on 

 each side, and five toes on all the feet. Its flattened tail, webbed hind- 

 feet, together with its aquatic habits and peculiar habitations, are described 

 in all popular works on natural history. Their fur is highly prized, and 

 much sought for, and it is now all but extinct in Europe. The substance 

 called Castor is a peculiar pungent secretion of a glandular pouch, termina- 

 ting in the prepuce ; and the organs of generation of both sexes terminate 

 within the rectum. 



The genus Helamys, P. Cuvier {Pedetes, Illiger), from South Africa, is 

 a peculiar animal, isolated in its position. It is called the jumping hare, 

 has a large head and eyes, a long tail, short fore-feet, with 5 toes, 

 having long pointed nails ; and lengthened hind-feet, with only four toes, 

 having large claws like hoofs. The mole-rats, Aspalacida, chiefly from 

 Africa, have the incisors broad, large and exserted; three molars as in 

 rats, heavy bodies with short limbs and tail, very small eyes, concealed 

 in some, and the ears small. They live underground, and feed entirely on 

 roots. Batliyergus, of South Africa, is made the type of a distinct family 

 by Blyth, Bathyergidm. They have four molars on each side, small eyes, 

 and a short tail. 



The pouched-rats are considered by some to form a distinct family, 

 equal in rank to the other four large families. They are the Saccomydides 

 of authors. They have four niolars on each side ; the upper incisors are 

 grooved ; the anterior median nails very long and trenchant. They have 

 deep cheek-pouches, opening externally, and are all from North America. 



Sub-fam. AKViooLiNiB, Voles, &c. 

 Snout blunt, rounded ; ears small, more or less concealed in the hair • 

 molars g_g, composed of alternating triangular prisms, without roots ; 

 incisors rounded ; tail generally short. 



