THE DORMOUSE OR SLEEPER 



353 



The skull resembles that of the Muridce, but the jugal bones 

 are larger, sometimes recalling those of the Sciuridcs ,- the 

 angular portions of the mandibles are bent 

 outwards at their centres so that their lower 

 borders bear distinct secondary angles. 



There are twenty teeth, arranged as — 



I - 1 



fim , m '^ — ^ 



i-i 3-3 



3 = 20. 



The premolars are small and single- Fig. 50.— Skull of Mus- 

 rooted. The molars decrease in size from -^f <^'«f aveiiananus (ij 



, , , , , times life size). 



the anterior to the posterior, the anterior 

 being distinctly the largest, and having five roots. All the cheek- 

 teeth have flat, highly polished surfaces, through which show 



ant. 



ant. 



ext. 



int. 



int. 



ext. 



post. post. 



Right upper. Right lower. 



Fig. 51. — Cheek-teeth of Muscardinus avellanarius, diagrammatic and magnified. 



complex, transverse or slightly oblique enamel folds, number- 



ing usually ^ — '- in the various teeth. The result is a 



3 — 6 — 6 — 6 



highly complicated, rasp-like surface, unique amongst mammals, 



but resembling in some few respects the teeth of elephants. 



THE DORMOUSE OR SLEEPER 



MUSCARDINUS A VELLANARIUS (Linnreus). 



1666. Mus AVELLANARUM, Christopher Merrett, Pinax, 167 ; Walker ; probably from 

 Aldrovandus, De Quadrupedibus Digitatis Viviparis, ii., 439, 1637. 



1693- Mus AVELLANARUM MINOR, John Ray, Synopsis Methodica Animalium 

 Quadrupedum, etc., 220. 



