470 RODENT! A 



begins. The whole body moves forward slowly, always advancing 

 in the same general direction in which they originally started, but 

 following more or less the course of the great valleys. They only 

 travel by night ; and, staying in congenial places for considerable 

 periods, with unaccustomed abundance of provender, notwith- 

 standing all the destructive influences to which they are exposed, 

 they multiply excessively during their journey, having families still 

 more numerous and more frequently than in their usual homes. 

 The progress may last from one to three years, according to the 

 route taken, and the distance to be traversed until the sea-coast 

 is reached, which in a country so surrounded by water as the 

 Scandinavian peninsula must be the ultimate goal of such a journey. 

 This may be either the Atlantic or the Gulf of Bothnia, according 

 as the migration has commenced from the west or the east side of 

 the central elevated plateau. Those that finally perish in the sea, 

 committing what appears to be a voluntary suicide, are only acting 

 under the same blind impulse which has led them previously to 

 cross smaller pieces of water with safety. 



Cuniculus. 1 Cranial and incisive characters those of Myodes, 

 in the main, but the molars more of an Arvicoline type, the first 

 upper one differing from that of all other members of the family in 

 having seven prisms. Externally of the general shape of Myodes, 

 but distinguished by the absence of external ears, the shortness and 

 dense furring of the feet, the obsolete pollex with rudimentary 

 nail, and the great length of the two middle claws of the manus. 

 Represented by one species, the Banded Lemming (C. torquatus), of 

 the Arctic region. 



Remains of both C. torquatus and Myodes lemmus occur in British 

 Pleistocene deposits. 



Fiber. 2 Closely allied to Arvicola, both externally and in cranial 

 and dental characters, but with the tail nearly as long as the body 

 (apart from the head), compressed, nearly naked, and reticulate. 

 Feet incompletely webbed, and the whole body adapted for a 

 thoroughly aquatic life. 



The Musk-Rat or Musquash (F. zibethicus, Fig. 209) is the only 

 representative of this genus, and the largest member of the sub- 

 family, the head and body being about 1 2 inches in length. It is 

 rather a heavily built animal, with a broad head, no distinct neck, 

 and short limbs ; the eyes are small, and the ears project very little 

 beyond the fur. The fore limbs have four toes and a rudimentary 

 thumb, all with claws ; the hind limbs are larger, with five distinct 

 toes, united by short webs at their bases. The tail is laterally 

 compressed, nearly naked, and scaly. The hair much resembles 

 that of a beaver, but is shorter ; it consists of a thick soft under- 



1 Wagler, Isis, 1832, p. 1220. 

 2 Cuvier, lAyms d' Anatomic Compar. tab. 1 (1800). 



