THE DORMOUSE OR SLEEPER 



353 



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

 are larger, sometimes recalling those of the Sciuridce ; 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 — 



O ,1-1 



c -, pm , 



O I - I 



Fig. 50. — Skull of Mus- 

 cardinus avellanarius (l| 

 times life size). 



The premolars are small and single- 

 rooted. The molars decrease in size from 

 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. 



p IG . c\. CHEEK-TEETH OF Muscardinus avellanarius, diagrammatic and magnified. 



complex, transverse or slightly oblique enamel folds, number- 

 ing usuallv 2 ~~ 5 7 6 in the various teeth. The result is a 

 s J 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 (Linnaeus). 



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

 Aldrovandus, De Quadrupedibus Digitatis Viviparis, ii., 439, l6 37- 



1693. Mus avellanarum minor, John Ray, Synopsis Methodica Animalium 

 Quadrupedum, etc., 220. 



