MAMMALS THAT GNAW. 99 



deposits of South Carolina, New Jersey, Tennessee, and other localities, as 

 well as in the cavern-deposits of Virginia and Pennsylvania. Within the 

 historic period its range extended from Alaska and the Hudson Bay terri- 

 tories in the north, along the Atlantic seaboard as far south as Georgia and 

 Northern Florida, and thence along the Gulf of Mexico as far as the Rio 

 Grande in Texas, and for some distance into Mexico itself, while on the 

 Pacific Coast it is known to have extended as far south as California and 

 Arizona. In the interior of the continent beavers were naturally confined to 

 the neighbourhood of the great lakes and river valleys. Writing in 1877 of 

 the American beaver, Dr. Allen observes that " its present range, however, 

 is much less extended, very few being found east of the Mississippi River 

 south of the great lakes, and it is everywhere less numerous than formerly. 

 Some still remain in Northern Maine and in the Adirondack region of New 

 York, and probably some still survive thence southward in the sparsely 

 settled districts to Alabama and Mississippi. A recent article states that 

 they are still abundant in portions of Virginia. Their existence in great 

 abundance throughout the Atlantic States, and thence westward to the 

 Pacific, is thoroughly attested. They having been less persistently hunted 

 during recent years than formerly, they are reported to be slowly on the 

 increase in most localities where they still remain." 



The dormice are the first representatives of the second section of the 

 Rodents, or Myomorpha, which presents the following characteristics. In 

 the skull the zygomatic arch is slender, and usually has the 

 jugal bone extending but little forwards, being supported by The Dormouse 

 a long backwardly directed process of the upper jaw-bone, Tribe. Family 

 or maxilla. There are no postorbital processes defining the Myoxidw. 

 hinder border of the socket of the eye ; and, except in one 

 sub-family of the 8palacidce, the angle of the lower jaw takes origin from the 

 inferior surface of the sheath of the lower incisor. All the members of the 

 section differ from the Sciuromorpha in that the tibia and fibula, or bones 

 of the lower leg, are welded together. 



Resembling the true squirrels in shape and habits, the dormice form an Old 

 World family of small arboreal Rodents characterised by their long hairy tail, 

 the large size of the ears and eyes, and the shortness of the fore-limbs. 

 There is but one pair of premolars in each jaw, and the molars are rooted 

 with transverse re-entering foldings of enamel on their crowns. The dormice 

 may be divided into two main groups, according to the structure of the 

 stomach. In Myoxus, as typified by M. glis of continental Europe, the 

 stomach is simple, but the different species, which have been arranged under 

 several generic heads, differ considerably in other respects. In the typical 

 species the bushy tail has the hairs arranged in a row on each side, while the 

 molars are large, with flat crowns and complex enamel-foldings. In a second 

 group (Eliomys), typified by the European M. nitella, and extending over 

 Europe, Asia, and Africa, the tail has the hairs arranged in two rows, but is 

 tufted at the end, while the molars are small, with concave crowns, and the 

 folds of enamel indistinct. The third group of the genus (Graphiurus) is 

 solely African, and is distinguished by the tail being short, cylindrical, and 

 tufted, while the enamel-foldings on the small molars are almost wanting. A 

 West African form (Claviglis) differs by the shorter and more distinctly tufted 

 tail. On the other hand, the common dormouse of England and the rest of 

 Europe (Muscardinus avellanarius') differs from all the foregoing in the 

 thickened glandular walls of the anterior portion of the stomach ; the 



